Publications

Andreas Schiller, Sandra Jenatsch, Balthasar Blülle, Miguel Angel Torre Cachafeiro, Firouzeh Ebadi, Nasim Kabir, Mostafa Othman, Christian Michael Wolff, Aïcha Hessler-Wyser, Christophe Ballif, Wolfgang Tress, and Beat Ruhstaller

The Journal of Physical Chemistry Letters, 15, 11252−11258.

DOI: 10.1021/acs.jpclett.4c02403

This research paper investigates the impact of illumination on ion conductivity in perovskite solar cells (PSCs), highlighting the complex interplay between ionic and electronic charge transport. Using drift-diffusion simulations to reproduce experimental impedance spectroscopy results, the authors discovered that the increase in capacitance observed at low frequencies under illumination is mainly caused by changes in electronic currents that emerge naturally as a consequence of the mixed electronic-ionic conduction in the perovskite. The simulations show how the changes in the alternating electronic currents occur due to the screening of the alternating electric field by oscillating ions within the active layer of the PSCs. 

A key contribution of this study is the introduction of a novel characterization technique to detect the presence of photo-enhanced ion conductivity. This technique is based on analyzing the frequency shift of the capacitance onset at different illumination intensities. The researchers extracted the frequency at which the capacitance reaches a specific value between the plateaus at lower and higher frequencies. By plotting the difference in the extracted frequency at various illumination intensities compared to in the dark, they observed distinct qualitative differences in the frequency shift patterns, depending on the presence of a photoconductive effect on the ions. 

The findings revealed that if there is no photoconductive effect, the derivative of the frequency shift decreases at lower illumination intensities. In contrast, in simulations mimicking a photoconductive effect, the derivatives increase with decreasing illumination intensity. To capture these distinct patterns, the technique requires a series of capacitance measurements over several orders of magnitude in illumination intensity. The illumination intensity range should be carefully chosen to observe both the constant derivative decrease and the change in the derivative at lower intensities. 

The researchers successfully applied this method to four different PSCs with varying active materials, confirming the presence of photo-enhanced ion conductivity in all the devices. This novel technique offers a simple and effective way to detect photo-enhanced ion conductivity in PSCs. It utilizes impedance measurements on fully integrated devices, making it practical for real-world applications. By contributing to a better understanding of the complex interplay between ionic and electronic charge transport, this technique can ultimately lead to improved device performance and stability. 

Fluxim's Setfos simulation software and Paios measurement platform were crucial to this research. Setfos enabled the creation of a drift-diffusion model of a PSC, simulating the behavior of the active layer—treated as a mixed electronic-ionic conductor—under different illumination conditions. This simulation was instrumental in understanding the influence of ionic charge carriers on capacitance and conductance. Paios, equipped with its calibrated white LED light source, was used to perform Electrochemical Impedance Spectroscopy (EIS) measurements on the PSCs to detect photoconductive effects on the ions. 

These findings emphasize the need for further research to develop a complete understanding of the phenomenon, as the interaction between ionic and electronic charge transport plays a significant role in the performance and stability of PSCs.

Lin, M. Y., Li, Q.-T., & Li, Y.-L. (2024).

IEEE Photonics Technology Letters, 36, 1730–1733. https://doi.org/10.1109/LPT.2024.3450713

This study investigates the impact of black matrix (BM) width on the performance of quantum dot full-color displays. The authors use theoretical calculations and simulations to evaluate how BM width affects crosstalk, the aliasing effect, and color gamut. They find that increasing the BM width from 0 nm to 25 nm can eliminate crosstalk between subpixels and significantly reduce the aliasing effect. This leads to a substantial improvement in color gamut, with the display featuring an Ag/ZnO/Ag structure achieving a color gamut ratio of 100.65% Adobe RGB and a coverage of 87.17%. The study highlights the importance of BM width optimization in quantum dot display design for achieving high image quality and wide color gamut. This research is particularly relevant for applications like small panels and head-mounted displays.

How Setfos was used

Setfos was used to model and optimize all of the MIM (metal-insulator-metal) layer models and to calculate the transmitted spectrum for the subpixels with the MIM layer.

Aeberhard, U., Natsch, N., Schneider, A., Zeder, S.J., Carrillo-Nuñez, H., Blülle, B. and Ruhstaller, B. (2024),

Sol. RRL 2400492.

https://doi.org/10.1002/solr.202400492

This research paper examines reverse-bias breakdown in all-perovskite tandem solar cells, particularly under partial shading conditions, and highlights how nonuniform active area quality, such as variations in mobile ion concentration, can impact their performance. The study uses a multi-scale simulation approach to demonstrate that an increase in mobile ion density significantly reduces the breakdown voltage and can lead to localized current hot spots in large-area modules. The authors suggest that these hot spots, caused by fluctuating mobile ion concentration, are potential degradation centers in the solar cells. They also suggest further investigation into factors like unintentional doping and additional breakdown mechanisms to better understand and improve the performance of these solar cells.

How SETFOS Was Used to Study Reverse-Bias Breakdown

The authors of the research paper use the device simulation tool SETFOS to perform cell-level simulations on all-perovskite tandem solar cells. Here's a breakdown of its role:

Drift-diffusion Simulation: SETFOS is used to simulate the behavior of charge carriers within the solar cell under a large reverse-bias voltage. This helps researchers visualize the band profile, or the energy levels of electrons within the device's various layers.

Mobile Ion Consideration: The simulations in SETFOS incorporate the effects of mobile ions within the perovskite layer, a crucial aspect that influences the breakdown voltage.

Coupling with Quantum Transport Simulation: The data from SETFOS, including the band profile and quasi-Fermi levels, are then used as input for a separate quantum transport simulation tool, PVnegf. This allows for a microscopic examination of the tunneling breakdown current.

Iterative Analysis: The tunnel generation rates, calculated in PVnegf, are fed back into SETFOS. This iterative process, with information exchanged between SETFOS and PVnegf, continues until the tunneling current converges, providing an accurate representation of the breakdown phenomenon.

Generating JV Curves: Through this coupled simulation approach, SETFOS ultimately helps generate current density-voltage (JV) curves for the all-perovskite tandem solar cell, even under reverse-bias conditions. These JV curves are essential for understanding how the device performs near its breakdown voltage.

In summary, SETFOS acts as the foundation for the cell-level simulations, providing crucial data about charge transport and mobile ion behavior, which is then combined with quantum transport calculations to comprehensively study reverse-bias breakdown in all-perovskite tandem solar cells.

Using Laoss to Simulate Large-Area Solar Module Behavior

Simon J. Zeder, Balthasar Blülle, Beat Ruhstaller, and Urs Aeberhard,  Opt. Express 32, 34154-34171 (2024)

https://doi.org/10.1364/OE.522953

This paper presents a multiscale optical model developed to accurately quantify photon recycling (PR) and luminescent coupling (LC) in optoelectronic devices such as solar cells and LEDs. Photon recycling, the process of photon emission, re-absorption, and re-emission, can significantly enhance device efficiency, particularly in materials like GaAs, metal halide perovskites and even crystalline silicon. To accurately account for re-absorption effects, the model treats light absorption and emission equally, considering the full spectrum of internal modes within the device. This approach stands out from conventional methods, which focus solely on exterior-coupled modes.

The framework integrates two key propagation models: 

Coherent Wave-Optical Model: Applied to thin-film layers where light interference effects are significant, avoiding unphysical divergencies for emitters embedded in absorbing media and ensuring consistency with detailed balance principles. 

Incoherent Ray-Optical Model: Used for optically thick layers where coherence is lost, treating phase relations as irrelevant. 

The model also accounts for light scattering at textured surfaces, essential for devices like perovskite –silicon tandem solar cells. By merging these approaches, the paper provides a robust framework for computing local emission, re-absorption, and energy flux rates in devices with complex structures. Importantly, this allows for a detailed understanding of the impact of photon recycling on device performance, including enhanced external quantum efficiency (EQE) in LEDs and increased open-circuit voltages in solar cells. 

The model is validated through comparisons with analytical solutions, showing excellent agreement, and applied to a textured perovskite solar cell showcasing its capabilities. This validation confirms that the model can reliably be applied to real-world devices, offering a powerful tool for optimizing the performance of next-generation optoelectronic systems. 

Key Takeaways: 

∙ Comprehensive multiscale approach merging coherent and incoherent light models. 

∙ Applicability to complex textured devices like perovskite solar cells and LEDs. 

∙ Quantification of local re-absorption and energy flux rates. 

∙ Validation through comparison with analytical solutions. 

W.-H. Hu, F. Nüesch, D. Giavazzi, M. Jafarpour, R. Hany, M. Bauer, . Adv. Optical Mater. 2024, 12, 2302105. https://doi.org/10.1002/adom.202302105

This research focuses on using squaraine dyes in single-component shortwave infrared (SWIR) photodiodes and upconversion photodetectors. These devices achieve over 40% external quantum efficiency beyond 1000 nm through field-assisted exciton dissociation. By integrating SWIR photodiodes with organic LEDs, they convert SWIR photons into visible light, offering an alternative to inorganic imaging technologies.

Key Points

Efficient SWIR Detection: Over 40% external quantum efficiency beyond 1000 nm.

Field-Assisted Charge Generation: Enables efficient exciton dissociation.

Upconversion Photodetectors: Combine SWIR photodiodes with OLEDs for visible light emission.

Simplified Fabrication: Single-component layers enhance stability and reduce complexity.

Inorganic Alternative: Potential replacement for existing inorganic SWIR imaging technologies.

How Setfos Was Used

Setfos was employed for optical simulations, analyzing device layer properties using refractive index and extinction coefficient values. These simulations optimized light absorption and exciton generation, crucial for efficient SWIR detection and upconversion.

Morteza Najarian, A., Vafaie, M., Chen, B. et al.

Nat Rev Phys6, 219–230 (2024).

https://doi.org/10.1038/s42254-024-00699-z

This paper from the research team at the University of Toronto reviews materials suitable for high-speed photodetectors, emphasizing their photophysical characteristics. It covers material classes such as organic semiconductors, perovskites, and quantum dots, discussing their performance metrics, advantages, and limitations for applications in high-speed optical communication and imaging technologies.

How Setfos was used

Simulations to understand the dynamics of electron traps were conducted using SETFOS software.

Othman, M., Jeangros, Q., Jacobs, D. A., Futscher, M. H., Zeiske, S., Armin, A., Jaffrès, A., Kuba, A. G., Chernyshov, D., Jenatsch, S., Züfle, S., Ruhstaller, B., Tabean, S., Wirtz, T., Eswara, S., Zhao, J., Savenije, T. J., Ballif, C., Wolff, C. M., & Hessler-Wyser, A. (2024). Energy & Environmental Science. The Royal Society of Chemistry.

DOI: https://doi.org/10.1039/D4EE00901K

This study investigates the effects of cationic alloying in cesium-formamidinium perovskite films on optoelectronic properties and solar cell performance. It finds that precise Cs+ tuning minimizes structural faults and enhances photoconductivity, with encapsulated devices maintaining 85% of initial efficiency after 1400 hours under continuous illumination, providing insights into defect tolerance and stability mechanisms in perovskite materials.

Fluxim's Research Tools

In the study, Fluxim's Paios system was used for conductivity measurements, and Litos for accelerated aging tests under thermal and photonic stress, evaluating the stability of perovskite solar cells.

Cachafeiro, Miguel A Torre, Naresh Kumar Kumawat, Feng Gao and Wolfgang Tress.

National Science Review (2024): nwae128

https://doi.org/10.1093/nsr/nwae128

The paper investigates the pulsed operation of perovskite LEDs (PeLEDs), focusing on the role of mobile ions in transient electroluminescence. Drift-diffusion simulations demonstrate how mobile ions affect the TrEL signals and device performance, with findings crucial for optimizing PeLED design and function.

How Setfos was used

The Setfos software was used to perform drift-diffusion simulations that modeled the behavior of mobile ions in perovskite LEDs. It analyzed their impact on transient electroluminescence and device performance, helping to elucidate the mechanisms affecting light emission during pulsed operation.

Almora, O., López-Varo, P., Escalante, R., Mohanraj, J., Marsal, L. F., Olthof, S., & Anta, J. A. (2024). arXiv:2402.00439 [physics.app-ph]

https://doi.org/10.48550/arXiv.2402.00439

The paper analyzes degradation in perovskite solar cells using impedance spectroscopy, focusing on NiOx passivation. It identifies how interface treatments influence device performance, with some treatments stabilizing and others inducing degradation. Simulation tools model transport properties to understand these effects.

How Setfos Was Used

Fluxim's Setfos simulation software was employed to model the transport properties and electrical responses of passivated-NiOx perovskite solar cells. This facilitated the understanding of how modifications at the hole transport layer-perovskite interface, due to various passivation methods, impact the cells' performance and operational stability.

Hou, Min-Chih and Luo, Dian and Huang, Yu-Ting and Liu, Shun-Wei and Lu, Chin-Wei and Chang, Chih-Hao and Su, Hai-Ching

Available at SSRN:

http://dx.doi.org/10.2139/ssrn.4608462

The study explores optimizing light extraction in light-emitting electrochemical cells (LECs) by adjusting the concentration of small TiO2 nanoparticles in a diffuser film. Enhanced roughness and appropriate refractive index improve light outcoupling, offering potential for higher device efficiencies in LEC lighting applications.

How Setfos was used

Fluxim's Setfos software was crucial in simulating light extraction efficiencies from LECs. By varying the TiO2 nanoparticle concentration in diffuser films, Setfos helped ascertain the optimal conditions for light outcoupling, demonstrating a significant enhancement in device performance with properly configured diffuser films.

A Boron, Nitrogen, and Oxygen Doped π-Extended Helical Pure Blue Multiresonant Thermally Activated Delayed Fluorescent Emitter for Organic Light Emitting Diodes That Shows Fast kRISC Without the Use of Heavy Atoms.

R. W. Weerasinghe, S. Madayanad Suresh, D. Hall, T. Matulaitis, A. M. Z. Slawin, S. Warriner, Y.-T. Lee, C.-Y. Chan, Y. Tsuchiya, E. Zysman-Colman, C. Adachi,

Adv. Mater. 2024, 2402289. https://doi.org/10.1002/adma.202402289

This study presents a boron, nitrogen, and oxygen-doped π-extended helical emitter for OLEDs that emits pure blue light efficiently without heavy metals. It demonstrates fast reverse intersystem crossing and high photoluminescence quantum yield, achieving narrow emission spectra close to the BT.2020 standard.

How Setfos was used

Setfos was used to analyze the orientation of transition dipole moments (TDM) within the films containing the MR-TADF emitter, f-DOABNA. This analysis is crucial for assessing how the TDM are oriented relative to the film surface, which affects the light outcoupling efficiency—a key factor in enhancing the performance of OLED devices.

Specifically, Setfos helped determine the horizontal-dipole ratios of f-DOABNA doped in different host materials. These ratios, varying between values indicative of perfectly horizontal to vertical orientation, provide insight into how efficiently the emitted light can be outcoupled from the OLED device. The results from Setfos showed that the emitter had a significant degree of horizontal alignment, especially in one host material, indicating better light outcoupling efficiency in that configuration.

Thiesbrummel, J., Shah, S., Gutierrez-Partida, E. et al.

Nat Energy (2024).

https://doi.org/10.1038/s41560-024-01487-w

The study reveals that the dominant factor in the degradation of perovskite solar cells (PSCs) under operational conditions is mobile ion-induced internal field screening, significantly reducing efficiency mainly due to current density reduction, without major bulk or interface quality degradation.

How Setfos was used

Setfos was used to simulate the impact of increasing mobile ion density on PSC performance, demonstrating that higher ion density leads to enhanced internal field screening, reducing charge extraction efficiency and contributing significantly to early degradation losses in PSCs.

T. Lee, M. Lee, K. Kim, H. Lee, S.-Y. Yoon, H. Yang, S. Yu, J. Kwak, Adv. Optical Mater. 2024, 2302509.

https://doi.org/10.1002/adom.202302509

This study presents angle-independent top-emitting quantum dot light-emitting diodes (QLEDs) featuring a solution-processed subwavelength scattering–capping layer (SCPL) composed of ZnO nanoparticles. This SCPL enhances light extraction and minimizes angle-dependent color shifts, achieving a 44% improvement in external quantum efficiency without perceivable spectral shifts across viewing angles. The dual functionality of the SCPL, serving both as a capping and scattering layer, introduces a simplified, cost-effective method for fabricating high-performance, angle-stable QLED displays.

How Setfos was used

Setfos was utilized to optimize the microcavity structure of blue-emitting QLEDs by adjusting the thickness of hole transport and electron transport layers, aiming for maximum light extraction efficiency and luminance. The tool's simulations guided the experimental verification of the device's optoelectronic performance, helping to achieve superior efficiency and color stability by precisely controlling the thickness of the scattering–capping layer (SCPL).

Zbinden, O., Knapp, E. and Tress, W. (2024), Sol. RRL 2300999.

https://doi.org/10.1002/solr.202300999

his study demonstrates how machine learning (ML) can pinpoint the parameters limiting efficiency in perovskite solar cells (PSCs) by analyzing current density–voltage curves from simulated devices. Over 11,000 simulated curves, varying 20 physical parameters related to charge transport and recombination, trained ML models to classify limiting parameters with over 80% accuracy. Random Forests showed the best performance, identifying key parameters like short-circuit current density, open-circuit voltage, and fill factor as critical for predictions. Applied to real device data, the model accurately identified efficiency-limiting factors, validating the approach's utility in guiding performance improvements and understanding device behavior, particularly during degradation. This methodology promises significant time and resource savings by reducing trial-and-error in PSC optimization.

How Setfos was Used

Setfos was used to generate about 11,150 current density–voltage (J–V) curves for perovskite solar cells by systematically varying one device parameter at a time, facilitating the training of machine learning algorithms to identify performance-limiting parameters based on these simulations.

E. Benvenuti, A. Lanfranchi, S. Moschetto, M. Natali, M. Angelini, P. Lova, F. Prescimone, V. Ragona, D. Comoretto, M. Prosa, M. Bolognesi and S. Toffanin,

J. Mater. Chem. C, 2024,

DOI: 10.1039/D3TC04321E.

This paper presents the development of an all-organic, on-chip integrated system for fluorescence detection, combining organic photodiodes (OPDs), organic light-emitting diodes (OLEDs), and a polymeric distributed Bragg reflector (DBR) filter. By integrating these components on a single substrate, the system offers a compact and efficient solution for fluorescence sensing, which is crucial for applications ranging from food safety to environmental monitoring. The use of organic materials allows for low-cost, flexible sensors that can be easily produced and deployed. The paper demonstrates that this integrated approach significantly enhances the optical efficiency and sensitivity of the fluorescence sensor, making it capable of detecting concentrations as low as 9.2 μM of the model dye Rhodamine 700. This advancement represents a significant step towards the development of portable, high-performance sensors for point-of-need applications​

How Sefos was used

Setfos was used to design the OLED structure to achieve an efficient and narrow phosphorescent emission, crucial for the integrated fluorescence sensor's performance. The simulation helped in fine-tuning the composition and thickness of the OLED's interlayers, including an organic index matching layer, to enhance light extraction and emission characteristics tailored to the absorption spectrum of the fluorescent dye, Rhodamine 700.

Xu, Ting and Jiang, Haixiao and Dong, Haojie and Zhao, Kele and Liang, Xiao and Sun, Yanqiu and Ding, Lei and meng, lingqiang and Meng, Hong,

Available at SSRN: https://ssrn.com/abstract=4610784

The study presents a novel approach to enhance blue MR-TADF OLEDs' efficiency and color purity using tandem device structures. By employing TBN-TPA as the blue MR-TADF material in tandem OLED devices, narrow-band emission and high color purity were achieved through optical interference and microcavity effects, aligning with BT 2020 standards. This advancement underscores the potential of tandem architectures and MR-TADF emitters in developing high-performance OLEDs with both high efficiency and wide color gamut, suggesting further research in optimizing tandem structures and MR-TADF materials.

How Setfos was used

Setfos software was utilized to simulate optical and electrical characteristics of OLED devices, particularly analyzing spectral enhancements, microcavity effects, and interference within the tandem OLED structures, to predict and understand device performance improvements, including color purity and efficiency.

Valastro, S., Calogero, G., Smecca, E., Bongiorno, C., Arena, V., Mannino, G., Deretzis, I., Fisicaro, G., La Magna, A. and Alberti, A. (2024), Sol. RRL 2300944.

https://doi.org/10.1002/solr.202300944

The research demonstrates printable carbon-based perovskite solar cells infiltrated with CsPbI3:EuCl3 outperform AVA-MAPbI3 cells, showcasing reduced hysteresis, stable efficiency under continuous light, and notable durability with multiple reusability cycles. Achieving a peak power conversion efficiency of 16.72%, the CsPbI3:EuCl3 variant emerges as a promising candidate for sustainable and efficient photovoltaic technologies, with implications for enhancing the environmental sustainability of solar energy generation​

How Setfos was used

Setfos tool was utilized for 1D transient-mode electro-optical simulations of the fabricated mesoporous carbon perovskite solar cells (mC-PSCs), incorporating both anion and cation migration within the active regions. This involved simulating the charge generation profile using the transfer-matrix method, calibrated with wavelength-dependent complex refractive indices of all layers, and coupling it with a drift-diffusion charge transport solver to account for charge trapping, recombination, and ion migration. The simulations aimed to replicate the measured J–V curves' main features, with layer-specific electrical parameters calibrated based on reasonable initial values from literature.

X. Zhang, J. Ràfols-Ribé, J. Mindemark, S. Tang, M. Lindh, E. Gracia-Espino, C. Larsen, L. Edman, Adv. Mater. 2024, 2310156.

https://doi.org/10.1002/adma.202310156

The paper by Zhang et al. investigates the decrease in emission efficiency at higher currents in light-emitting electrochemical cells (LECs). It focuses on identifying and quantifying the major factors causing this efficiency drop, such as outcoupling efficiency and exciton quenching. The study presents a method to analyze these factors, contributing to the design of more efficient, high-luminance LEC devices.

How Setfos was used

Setfos was used for modeling in the study. This software simulated the structure of the light-emitting electrochemical cell (LEC) device, including various components like the glass substrate, ITO anode, active material, and Al cathode. The software modeled excitons as emissive electrical dipoles. It was particularly used for simulating the electroluminescence (EL) spectra and EL intensity to determine the position of the emissive p-n junction in the device, using a delta function exciton distribution in a transparent, non-doped active material with the wavelength-dependent refractive index of pristine Super Yellow

S. Ravishankar, L. Kruppa, S. Jenatsch, G. Yan and Y. Wang, Energy Environ. Sci., 2024,

DOI: 10.1039/D3EE02013D.

The paper discusses a novel method for analyzing solar cell operation, focusing on perovskite solar cells (PSCs). It addresses a gap in understanding the equivalence of time-domain and frequency-domain data in solar cell analysis. The study introduces a new approach to extract a previously inaccessible time constant from frequency domain data, which correlates with charge extraction speed in transient measurements. This method is validated through simulations and experimental data, offering a more comprehensive understanding of charge carrier dynamics in solar cells, particularly regarding charge collection efficiency.

How Setfos was used

SETFOS was utilized in the paper for conducting drift-diffusion simulations. These simulations were part of the study's methodology to characterize perovskite solar cells (PSCs) using various techniques, including transient photovoltage (TPV), transient photocurrent (TPC), intensity-modulated photovoltage spectroscopy (IMVS), intensity-modulated photocurrent spectroscopy (IMPS), and impedance spectroscopy (IS)​

Elkhouly, K., Goldberg, I., Zhang, X. et al.

Nat. Photon. (2024).

https://doi.org/10.1038/s41566-023-01341-7

Imec's research, published in Nature Photonics, details the creation of a perovskite LED stack that dramatically outshines conventional OLEDs.

The team used Setfos to analyze and optimize the light interactions within the perovskite structure. This approach significantly enhanced the LED's brightness and efficiency. The breakthrough paves the way for high-intensity, thin-film perovskite lasers with potential applications in medical diagnostics, environmental sensing, and advanced imaging, heralding a new era in optoelectronic devices. Setfos was instrumental in achieving the precise architecture needed for this revolutionary leap in light-emitting technology.

S. Tang, J. M. dos Santos, J. Ràfols-Ribé, J. Wang, E. Zysman-Colman, L. Edman, Adv. Funct. Mater. 2023, 33, 2306170. https://doi.org/10.1002/adfm.202306170

The paper introduces MR-TADF emitters into light-emitting electrochemical cells (LECs) for narrowband and efficient emission. It demonstrates a metal-free MR-TADF LEC delivering blue light with a narrow full-width-at-half-maximum (FWHM) of 31 nm, a high external quantum efficiency of 3.8%, and significant electrochemical doping capacity.

How Setfos was used

Setfos was used to perform optical simulations, helping to understand and optimize the emission and efficiency of the device by simulating the position of emissive dipoles within the active material.

Zhang, T., Zhao, F., Liu, P., Tan, Y., Xiao, X., Wang, Z., Wang, W., Wu, D., Sun, X.W., Hao, J., Xing, G. and Wang, K. (2023)

Adv. Photonics Res., 4: 2300146.

https://doi.org/10.1002/adpr.202300146

The paper investigates electron leakage in green InP Quantum-Dot Light-Emitting Diodes (QLEDs), causing carrier imbalance and reduced efficiency. It identifies the Fermi energy difference between green InP/ZnS Quantum Dots and the ITO anode as the main cause.

How Setfos was used

Setfos was used for electrical simulations of recombination rates, helping to understand electron leakage paths and the impact of an ultrathin LiF layer, which ultimately improves device performance by enhancing electron confinement and hole injection.

S. Alam, H. Aldosari, C. E. Petoukhoff, T. Váry, W. Althobaiti, M. Alqurashi, H. Tang, J. I. Khan, V. Nádaždy, P. Müller-Buschbaum, G. C. Welch, F. Laquai

Adv. Funct. Mater. 2023, 2308076. https://doi.org/10.1002/adfm.202308076

This paper investigates the impact of thermal annealing on PM6:Y6-based organic solar cells, focusing on performance degradation due to structural and morphological changes at elevated temperatures. It finds that VOC and FF significantly decrease with annealing above 140°C due to altered charge transport and extraction.

How Setfos was used

Using SETFOS software, the study simulates device performance, correlating optical-electrical properties with device parameters to understand the degradation mechanisms and guide future improvements.

How Paios was used

Paios was used to measure transient photocurrent, photo-voltage, and charge extraction properties, providing insights into charge generation, recombination, and extraction mechanisms, helping to understand the performance drop at elevated annealing temperatures.

S. Sasaki, K. Goushi, M. Mamada, S. Miyazaki, K. Miyata, K. Onda, C. Adach Adv. Optical Mater. 2023, 2301924. https://doi.org/10.1002/adom.202301924

The paper explores intramolecular triplet–triplet annihilation (TTU) upconversion in organic light-emitting diodes (OLEDs) for enhanced electroluminescence efficiency. The study focuses on the intramolecular TTU of anthracene dimers in OLEDs, showing improved electroluminescence efficiency under low dopant concentrations.

How Setfos was used

Setfos was utilized to estimate the out-coupling efficiency of the OLEDs, contributing to the understanding of the TTU process and device optimization.

Q. Wang, H. Zhu, Y. Tan, J. Hao, T. Ye, H. Tang, Z. Wang, J. Ma, J. Sun, T. Zhang, F. Zheng, W. Zhang, H. W. Choi, W. C. H. Choy, D. Wu, X. W. Sun, K. Wang. Adv. Mater. 2023, 2305604.

https://doi.org/10.1002/adma.202305604

The paper demonstrates a spin quantum dot light-emitting diode (spin-QLED) using 2D chiral perovskite as a spin injection layer based on the chiral-induced spin selectivity (CISS) effect, enabling spin-dependent carrier transport. It operates at room temperature and zero magnetic field, achieving circularly polarized electroluminescence (CP-EL) with an asymmetric factor of 1.6 × 10^-2. The work highlights the potential of chiral materials in spintronics and quantum-based devices.

How Setfos was used

Setfos simulation was used to analyze the recombination center and carrier recombination rate distribution in the device, providing insights into the performance and guiding future improvements.

Darshan H. Parmar, Benjamin Rehl, Ozan Atan, Sjoerd Hoogland, and Edward H. Sargent

ACS Applied Materials & Interfaces Article ASAP

DOI: 10.1021/acsami.3c14611

Colloidal quantum dot photodetectors exceed silicon's limits by detecting longer wavelengths, with performance depending on the ligand concentration during processing. This study connects simulated and actual photocurrent responses, showing that different ligand concentrations uniquely impact trap state density and device behavior.

How Setfos was used

Setfos was used to show how the transient measurements were consistent with a changing trap density in the photodetector active layer with respect to ligand exchange concentration.

Qi Dong, Liping Zhu, Shichen Yin, Lei Lei, Kenan Gundogdu, and Franky So

ACS Photonics 2023 10 (9), 3342-3349

DOI: 10.1021/acsphotonics.3c00812

Researchers have developed a highly efficient linearly polarized organic LED, capitalizing on the inherent polarization properties of the transverse electric waveguide mode within the device. Utilizing a linear grating, they achieved 67.6% light confinement in this mode, resulting in a polarized LED with a current efficiency of 136 cd/A and a polarization ratio exceeding 30. Further enhancements to current efficiency are possible, making this architecture adaptable for various thin-film LED applications in photonics.

How Setfos was used

The researchers used Setfos for optical simulations to analyze the spatial distribution of different modes in the top-emitting OLED device, determine the optimized device geometry, and simulate the dissipated power versus the effective refractive index in the optimized condition to enhance the efficiency of polarized emission.

Bandgap Tunable Perovskite for Si-Based Triple Junction Tandem Solar Cell: Numerical Analysis-Aided Experimental Investigation

Jia-Ci Jhou, Ashish Gaurav, Hsin-Ting Lin, and Ching-Fuh Lin

ACS Applied Energy Materials 2023 6 (18), 9434-9445

DOI: 10.1021/acsaem.3c01344

Researchers developed a new technique to fabricate perovskite absorbing layers for multijunction solar cells, achieving a record power conversion efficiency of 26.4%. This technique involves a double-sided sandwich evaporation process that allows for precise control over the halide ratio and B-site doping of the perovskite absorber layers. The resulting triple-junction tandem solar cell exhibits significantly higher efficiency than previous designs.

How Setfos was used.

theoretical insight for the optimal perovskite thickness was gained using Setfos by taking into account the reflection of the bottom cell, so the thickness of the top layers could be reduced.

Warby, J., Shah, S., Thiesbrummel, J., Gutierrez-Partida, E., Lai, H., Alebachew, B., Grischek, M., Yang, F., Lang, F., Albrecht, S., Fu, F., Neher, D., Stolterfoht, M.,

Adv. Energy Mater. 2023, 2303135.

https://doi.org/10.1002/aenm.202303135

This research addresses the discrepancy between open-circuit voltages (VOC) and internal voltages in perovskite solar cells, often attributed to non-radiative recombination losses. The study extends classical theories from silicon solar cells to explain the mismatch through partial resistances/conductivities of carrier types. It also reveals how mobile ions in perovskite cells contribute to this mismatch, explaining phenomena like light soaking and aging-induced VOC losses. These insights offer new perspectives on degradation issues and guide principles for optimizing VOC to enhance perovskite solar cell performance.

How Setfos was used

Band diagram simulation of perovskite cells with ions

Moritz C. Schmidt, Emilio Gutierrez-Partida, Martin Stolterfoht, and Bruno Ehrler

PRX Energy 2, 043011 – Published 13 November 2023

https://doi.org/10.1103/PRXEnergy.2.043011

This study reveals that analyzing capacitance transients in perovskite solar cells is more complex than previously thought. It demonstrates that the direction of these transients is influenced by the cell's layer dominating capacitance modulation, not by the polarity of migrating species. This highlights the significant role of transport layers in characterizing mobile ions in perovskites.

Setfos was used

To investigate the role of the polarity of mobile ions in capacitance measurements the researchers simulated the behavior of the capacitance as a function of time after a voltage pulse. The Drift-Diffusion module in Setfos was used to simulate the capacitance transients.

Hye In Yang, Nagarjuna Naik Mude, Jin Young Kim, Jun Hyeog Oh, Ramchandra Pode, and Jang Hyuk Kwon,

Opt. Express 31, 18407-18419 (2023)

https://doi.org/10.1364/OE.487301

The study presents an enhanced top emission OLED (TEOLED) device structure that significantly improves light extraction, specifically by addressing waveguide mode loss in the thin film encapsulation (TFE) layer. By introducing a low refractive index (RI) layer between the capping layer (CPL) and the aluminum oxide (Al2O3) layer, the device manipulates evanescent waves to redirect trapped light within the device, increasing its extraction. This novel TFE structure (CPL/low RI layer/Al2O3/polymer/Al2O3) led to a 23% increase in current efficiency and a 26% enhancement in the blue index value for the blue TEOLED device. This method shows significant potential for advancing flexible optoelectronic device encapsulation technologies.

How Setfos was used

SETFOS 5.1 is used as an optical simulator. The RI of the glass substrate, indium tin oxide (ITO), and organic layers are taken as ∼1.5, 1.8∼2.0, and ∼1.8, respectively. The RI and extinction coefficient of silver (Ag) and magnesium (Mg):Ag (10:1) used as an anode and cathode, respectively, are taken from the reported values. For the EML, the thin film photoluminescence spectrum of 2,12-di-tert-butyl-N,N,5,9-tetrakis(4-(tert-butyl)phenyl)-5,9-dihydro-5,9-diaza-13bboranaphtho[ 3,2,1-de]anthracen-7-amine (DABNA-NP-TB) for the blue TEOLED device, bis[2- (2-pyridinyl-N)phenyl-C](acetylacetonato)iridium(III) for the green TEOLED device, and (bis(4- methyl-2-(3,5-dimethylphenyl)quinoline))Ir(III (tetramethylheptadionate) for the red TEOLED device are used.

Dian Luo, Wei-Yu Chen, Wei-Lun Syu, Shun-Wei Liu, and Chih-Hao Chang

ACS Photonics 2023 10 (8), 2874-2885

DOI: 10.1021/acsphotonics.3c00590

The study introduces four innovative design strategies for tandem organic light-emitting diodes (TOLEDs) to overcome the efficiency loss caused by charge-generation layer (CGL) interactions in multi-layer devices. The designs include an optimized CGL, an exciplex host in the emitting layer for improved carrier balance and reduced voltage, simplified architecture, and nanoparticle diffusers. These led to a three-stacked TOLED reaching 78.7% efficiency, 2.5 times higher than conventional devices. Adding a nanoparticle diffuser further increased efficiency to 123.9%, with a record luminance of 411,531 cd/m². The findings show promise for TOLEDs in OLED phototherapy and display applications with high efficiency and luminance.

How Setfos was used

Setfoswas chosen as the calculation tool for the external optical coupling of the devices.

Luo, D., Hou, M.-C., Wang, K.-Y., Chang, C.-H., Liu, S.-W., Lu, C.-W. and Su, H.-C. (2023),

Adv. Mater. Technol., 8: 2300563. https://doi.org/10.1002/admt.202300563

The research presents a tandem white OLED/LEC hybrid device, combining a red OLED and a blue LEC, which simplifies fabrication compared to multi-layered OLEDs. The device includes a charge-generating layer (CGL) that not only links the two, but also improves carrier balance, leading to an external quantum efficiency (EQE) of 21.53%. Efficiency jumps to 37.88% when using a diffusive substrate. This demonstrates a simpler yet highly efficient structure, offering promising potential for cost-effective lighting solutions.

How Setfos was used

To clarify the relationship between the recombination zone position and the optical mode distribution for Device B, Device R, and Device T. The optical simulation software Setfos was employed as the analysis tool as was the optical mode distribution of the devices.

Huseynova, G., Ràfols-Ribé, J., Auroux, E. et al. Sci Rep 13, 11457 (2023).

https://doi.org/10.1038/s41598-023-38006-y

The performance of light-emitting electrochemical cells (LECs) is greatly influenced by the position of the emissive p–n junction within the device. A new "chemical pre-doping" method that incorporates a reductant into the active material ink shifts the p–n junction closer to the anode, which enhances emission efficiency and device stability. This approach offers a practical solution for optimizing the spatial configuration of p–n junctions in LECs.

How Setfos was used

The optical simulations were carried out with Setfos. The position of the emissive p–n junction within the active material was determined by minimizing the root mean square error between the simulated and the measured angle-dependent EL data.

The exciton formation rate profile in the interelectrode gap was determined with the drift–diffusion module of the same software, and the simulated three-layer device featured an ITO anode (thickness = 145 nm), an active material (thickness = 150 nm), and an Al cathode.

Yan-Yun Jing et al. ,Sci.Adv.9, eadh8296(2023). DOI:10.1126/sciadv.adh8296

Here the researchers have developed a new strategy to create red Multiple Resonance (MR) emitters for OLEDs achieves high efficiency and color purity by adjusting the π-conjugation and electron-donating properties within a boron-based structure. The result is a range of emissions with narrow bandwidths and a particularly pure-red device meeting the BT.2020 standard with high quantum efficiency and brightness. This approach suggests a promising direction for developing OLED materials with superior color performance.

How Setfos was used

The experimental EQEs closely aligned with the theoretical efficiencies predicted by optical simulations using Setfos software (33.6% for CzIDBNO and 27.9% for IDIDBNO), which further demonstrated the intricate interplay of these parameters on outcoupling efficiency and overall device performance.

Yu Zhang, Weiqing Nie, Mengli Hu, Wu Liu, Heng Liu, Xiaomin Huo, Yao Lu, Dandan Song, Bo Qiao, Zhiqin Liang, Zhiqiang Jiao, Zheng Xu, Guangcai Yuan, and Suling Zhao

ACS Photonics 2023 10 (10), 3521-3530

https://doi.org/10.1021/acsphotonics.3c00524

This research outlines the advancement in tandem optoelectronic devices, specifically a perovskite/organic quasi-tandem system for narrowband photodetectors (NPDs) targeting the visible to near-infrared spectrum. By varying the composition of perovskite and organic layers, the spectral response is tunable, enhancing device selectivity and flexibility. Achieving a peak response near 790 nm with a 41 nm bandwidth, these NPDs exhibit rapid submicrosecond response times, significantly outperforming traditional thick-layer photodetectors, marking a step forward in the development of ultra-fast NPDs.

How Setfos was used

Setfos was utilized to stimulate the penetration of different monochromatic light, the thickness of perovskite (MAPbI3) was set as 1700 nm, and a 150 nm of organic blend layer (PM6:IT-4F) was set on the perovskite. Take thickness as the scanning parameter, with a step size of 10 nm. The optical parameters (n, k) of the materials are obtained through an ellipsometer.

Noel C. Giebink and Stephen R. Forrest

Phys. Rev. Lett. 130, 267002 – Published 29 June 2023

https://doi.org/10.1103/PhysRevLett.130.267002

The study establishes a thermodynamic limit for OLED efficiency, revealing that OLEDs require higher voltage for the same brightness compared to inorganic LEDs due to strong exciton binding. Optimizing factors like low exciton binding energy, long exciton lifetime, and efficient electron-hole recombination can minimize OLED overpotential, suggesting top-performing OLEDs may be near their efficiency limit. This framework aids in developing low-voltage OLEDs for displays and lighting.

How Setfos was used

Setfos was used to validate the theoretical model considering also exciton dissociation.

Juhui Oh, Ju-Hyeon Kim, Yong Ryun Kim, Ardalan Armin, Sanseong Lee, Kiyoung Park, Hongkyu Kang, and Kwanghee Lee

ACS Applied Materials & Interfaces 2023 15 (36), 42802-42810

https://doi.org/10.1021/acsami.3c08028

This research discusses the challenge of balancing transparency and efficiency in transparent organic solar cells (T-OSCs) for smart solar windows. A new tungsten oxide (WO3)-based multilayer top electrode is presented that achieves both high photopic transmittance (46.7%) and power conversion efficiency (7.0%), with superior light utilization and thermal stability. This development offers new directions for creating efficient, transparent solar cells for energy-harvesting windows.

How Setfos was usedSetfos

To predict the transparent OSC performance, optical simulation was conducted with the commercial software Setfos using n and k values obtained from ellipsometry.

Jinno, H., Shivarudraiah, S. B., Asbjörn, R., Vagli, G., Marcato, T., Eickemeyer, F. T., Pfeifer, L., Yokota, T., Someya, T., Shih, C.-J.,

. Adv. Mater. 2023, 2304604.

https://doi.org/10.1002/adma.202304604

This research presents a breakthrough in ultrathin, flexible skin optoelectronics for Internet of Things (IoT) applications. Traditional issues like underperformance due to low polymer process temperatures and spectral distortion from bending are overcome using solution-processed perovskite semiconductors. The study introduces high-efficiency perovskite solar cells and LEDs on polymer films with exceptional thermal stability, achieving record efficiencies (18.2% for solar cells, 15.2 cd A−1 for LEDs) and bending-resistant light emission. This advancement enables reliable, high-performance, self-powered wearables and IoT sensors, demonstrating practical applications such as accurate pulse monitoring at a high selectivity rate.

How Setfos Was used

Finite element analysis for ultraflexible LED was simulated with the Setfos emission module. By expecting the dipole emission model of LED, the module allows to deliver emission spectra of ultraflexible LED with different angle.

Dr. Camilla Arietta VAEL-GARN

Ph. D Thesis, EPFL , 12 Sept. 2023

https://doi.org/10.5075/epfl-thesis-10350

The study explores polymeric semiconductors in organic electronics, using drift-diffusion simulation to study three areas. First, the applicability of thermally stimulated current measurement for studying trap states in organic semiconductors is investigated, identifying a reliable formula for data analysis. Second, reversible trap states in a polymeric light-emitting diode are studied, suggesting trap state formation and disaggregation may involve water and oxygen molecules. Lastly, the operational principles of an upconverter device converting near infra-red to visible light are examined, finding that electron mobility in the emission layer significantly affects the device's response time.

Han Bin Cho, Ju Yeon Han, Ha Jun Kim, Noolu Srinivasa Manikanta Viswanath, Yong Min Park, Jeong Wan Min, Sung Woo Jang, Heesun Yang, and Won Bin Im

ACS Appl. Mater. Interfaces 2023, 15, 24, 29259–29266, June 8, 2023

https://doi.org/10.1021/acsami.3c02857

Quantum dot light-emitting diodes (QLEDs) often use PEDOT:PSS as a hole injection layer (HIL), but it has a high energy barrier for hole injection, resulting in low efficiency. Researchers improved device efficiency by using a bilayer HIL with VO2 and PEDOT:PSS, achieving an 18% external quantum efficiency, 78 cd/A current efficiency, and 25,771 cd/m² maximum luminance, compared to 13%, 54 cd/A, and 14,817 cd/m² for the PEDOT:PSS-based QLED. This approach effectively reduced the energy barrier between indium tin oxide (ITO) and PEDOT:PSS, boosting QLED efficiency.

How Setfos was used

The optical simulation was conducted using the advanced simulation software Setfos.

Sarmad Feroze, Andreas Distler, Karen Forberich, Iftikhar Ahmed Channa, Bernd Doll, Christoph J. Brabec, Hans-Joachim Egelhaaf,

Solar Energy, Volume 263, 2023, 111894, ISSN 0038-092X,

https://doi.org/10.1016/j.solener.2023.111894

The 2022 global PV installations accounted for 5% of electricity consumption. To reach 2 TWP annually by 2030, leveraging existing urban surfaces is vital. BAPV/BIPV transform buildings into energy producers. Currently dominated by silicon PV modules, the market has underutilized Organic Photovoltaics (OPV), a cost-effective, customizable, and flexible alternative for BIPV applications. This study analyzes OPV's outdoor performance compared to monocrystalline silicon modules, aiming to provide insights for forecasting the annual energy yield of building-integrated OPV modules, advancing OPV technology for BIPV applications.

How Setfos was used

Setfos software by Fluxim AG was used for optical simulations to evaluate absorption in the active layer of the OPV device.

Sandheep Ravishankar, Zhifa Liu, Yueming Wang, Thomas Kirchartz, and Uwe Rau

PRX Energy 2, 033006 – Published 2 August 2023

https://doi.org/10.1103/PRXEnergy.2.033006

Researchers present a model for the frequency and time domain optoelectronic response of perovskite solar cells (PSCs). The model emphasizes the role of charge carrier exchange between the perovskite and the transport layer. The study identifies that the time constants measured in the frequency domain spectra of PSCs are mainly influenced by the charge carrier extraction velocity at the perovskite/transport layer interfaces, rather than recombination. This understanding is crucial for quantifying recombination and resistive losses that impact the performance of the solar cell.

Drift-diffusion simulations are performed using SETFOS developed by Fluxim AG

Li, G., Pu, J., Yang, Z., Deng, H., Liu, Y., Mao, Z., Zhao, J., Su, S., Chi, Z., Aggregate 2023, 00, e382.

https://doi.org/10.1002/agt2.382

This study proposes a design strategy for constructing highly efficient organic light-emitting diodes (OLEDs) using thermally activated delayed fluorescence (TADF) emitters with high horizontal dipole ratios. The researchers designed two TADF emitters, BO-3DMAC and BO-3DPAC, using a shamrock-shaped structure. These emitters exhibited high horizontal dipole ratios of 84-93% in both neat and doped films. The emitters showed excellent external quantum efficiencies (EQEs) of up to 38.7% in doped OLEDs with sky-blue emission. The researchers also demonstrated that the shamrock-shaped design resulted in aggregation-induced emission (AIE) and low efficiency roll-off. The emitters had low singlet-triplet energy splitting (ΔEst) and achieved high PLQYs. The results highlight the potential of the shamrock-shaped design to construct TADF emitters with high Θ// and pave the way for the development of high-performance OLEDs.

How Setfos was used

The refractive index of the materials were extracted from the Setfos database and the light out-coupling efficiency of devices were also simulated.

Wang, J, Xie, M, Pang, H, Zhang, C, Sang, M, Zhang, Q, et al.

J Soc Inf Display. 2023; 31( 6): 457– 465.

https://doi.org/10.1002/jsid.1205

This scientific article discusses the development of high-performance red and green phosphorescent emitters suitable for the BT.2020 color gamut in displays. The researchers conducted optical simulations to determine the optimal spectra for the emitters. For the green emitter, they found that a spectrum with a peak wavelength at 526 nm and a full width at half maximum (FWHM) less than 30 nm could achieve the desired color coordinates. For the red emitter, they discovered that decreasing the FWHM instead of red-shifting the spectrum was important to achieve the desired color coordinates while maintaining high current efficiency. Based on these simulation results, the researchers designed and synthesized novel deep green (DGD) and deep red phosphorescent (DRD-II) emitters. The DGD emitter achieved a color coordinate of (0.170, 0.777) with a current efficiency of 171 cd/A, and the DRD-II emitter achieved a color coordinate of (0.708, 0.292) with a current efficiency of 59 cd/A. The researchers also demonstrated that the angular dependence of these devices was comparable to those with commercial emitters. Overall, these findings suggest that phosphorescent emitters have the potential to meet the BT.2020 color standard in organic displays.

How was Setfos used?

SETFOS 5.0 was used for optical simulations to determine the optimal spectrum of a green emitter suitable for BT.2020. The simulations involved employing a series of simulated green photoluminescence (PL) spectra. Optical constants, such as the refractive index and the extinction coefficient of each emitter, were taken into account during the simulations.

Jonas Diekmann, Francisco Peña-Camargo, Nurlan Tokmoldin, Jarla Thiesbrummel, Jonathan Warby, Emilio Gutierrez-Partida, Sahil Shah, Dieter Neher, and Martin Stolterfoht

The Journal of Physical Chemistry Letters 2023 14 (18), 4200-4210

DOI: 10.1021/acs.jpclett.3c00530

This scientific article discusses the impact of mobile ions on perovskite photovoltaic devices and the challenges in accurately quantifying mobile ion densities. The study evaluates several experimental methodologies, including charge extraction by linearly increasing voltage (CELIV) and bias-assisted charge extraction (BACE), as well as frequency-dependent capacitance measurements.

The findings show that CELIV underestimates ion density and is not suitable for accurate quantification. BACE, on the other hand, can accurately reproduce ion density as long as it is lower than the electrode charge. The study also demonstrates that low-frequency Mott-Schottky analysis can provide accurate ion density values for high excess ionic densities typical of perovskites. Overall, the methods presented in this study enable accurate tracking of ionic densities in perovskite devices and a deeper understanding of ionic losses and device aging.

How was Setfos Used?

SETFOS was used in this work to simulate the impact of mobile ions on the performance of perovskite solar cells. The parameters related to mobile ions were implemented in the drift-diffusion module of Setfos. This allowed the researchers to include mobile ions in their simulations and recreate the observed JV-hysteresis in the cells over a wide range of scan speeds. The simulations also verified that losses in the performance characteristics of JSC, VOC, and FF could be recreated

Kamijo, T., van Breemen, A.J.J.M., Ma, X. et al. A touchless user interface based on a near-infrared-sensitive transparent optical imager. Nat Electron (2023).

https://doi.org/10.1038/s41928-023-00970-8

Researchers have developed a touchless user interface based on a visually transparent near-infrared-sensitive organic photodetector (OPD) array. The touchless interface can be used on top of a display, eliminating the need for physical contact.

The OPD array is designed with optical transparency in mind, using printed copper grids and patterned organic photodetector subpixels. The design optimization results in a high photodetectivity of 10^12 Jones at 850 nm and a visible-light transmittance of 70%.

The touchless user interface can be used with a penlight or through gesture recognition, providing a hygienic and convenient alternative to traditional touch screens. The technology has potential applications in automated teller machines (ATMs), ticket vending machines, and kiosks, where hygiene is a concern. It is a scalable and flexible solution that can be integrated into a variety of display applications without size limitations or calibration requirements. 2D FEM simulations for the surface potential and the current density distributions derived from the printed Cu grid structure .

How Fluxim’s Research Tools were used

Setfos

Numerical electro-optical simulations for the photogenerated J–V curves of our NIR-sensitive OPDs were performed by using Setfos.

The VLT of the parallel OPD subpixel array was calculated by the summation of the simulated optical transmittance for each component using Setfos

Laoss

2D FEM simulations for the surface potential and the current density distributions derived from the printed Cu grid structure for our NIR-sensitive OPDs were performed by Laoss 4.0

Metikoti Jagadeeswararao, Kyu Min Sim, Sangjun Lee, Mingyun Kang, Sanghyeok An, Geon-Hee Nam, Hye Ryun Sim, Elham Oleiki, Geunsik Lee, and Dae Sung Chung

Chemistry of Materials 2023 35 (8), 3095-3104

DOI: 10.1021/acs.chemmater.2c03271

This study demonstrates high-performance photomultiplication (PM)-type photodetectors using lead-free double perovskite, achieved by engineering trap states and trap-assisted charge injection. With a diode structure, the researchers realized selective hole traps, leading to high external quantum efficiency (EQE) of ∼16,000%, responsivity of ∼50 A W−1, and specific detectivity over 10¹² Jones at -3V. The work highlights PM photodetectors' potential through strategic trap engineering.

Setfos, a Fluxim software, was used for drift-diffusion simulations to gain comprehensive insight into the photomultiplication mechanism in the proposed photodetector.

Ràfols-Ribé, J., Hänisch, C., Larsen, C., Reineke, S. and Edman, L. Adv. Mater. Technol. 2202120.

https://doi.org/10.1002/admt.202202120

This study explores emissive dipole orientation in light-emitting electrochemical cells (LECs) affecting emission efficiency. Using a destructive-interference microcavity method, researchers find ≈95% horizontal dipole orientation in LECs with Super Yellow emitters, enabling efficient photon outcoupling, despite strong perpendicular electric fields and ion motion.

LEC Optical Modeling and Fitting: The LEC devices were simulated with a Setfos.

Lee, J. H., Huang, J.-X., Chen, C.-H., Lee, Y.-T., Chan, C.-Y., Dzeng, Y.-C., Tang, P.-W., Chen, C., Adachi, C., Chiu, T.-L., Lee, J.-H., Chen, C.-T.,

Adv. Optical Mater. 2023, 2202666.

https://doi.org/10.1002/adom.202202666

Researchers have designed and synthesized a novel near-ultraviolet (NUV) fluorescent material, BB4Ph, based on the classic 1,1′:4′,1″-terphenyl fluorophore. The material exhibits high order and horizontal-dipole ratios, enabling efficient NUV organic light-emitting diodes (OLEDs). Non-doped BB4Ph OLEDs achieved external quantum efficiency (EQE) up to 5.24%, while doped BB4Ph OLEDs with 4P-Cz reached a peak EQE of 6.99%. The material's high photoluminescence quantum yield and light outcoupling efficiency make it a promising candidate for NUV OLED applications.

Hsieh CA, Tan GH, Chuang YT, Lin HC, Lai PT, Jan PE, Chen BH, Lu CH, Yang SD, Hsiao KY, Lu MY, Chen LY, Lin HW.

Adv Sci (Weinh). 2023 Feb 7:e2206076.

doi: 10.1002/advs.202206076

Researchers have significantly improved the efficiency of vacuum-deposited metal halide perovskite light-emitting diodes (PeLEDs) by optimizing the stoichiometric ratio of sublimed precursors and incorporating ultrathin layers. The properties of these perovskite layers are highly influenced by the presence of upper- and presublimed materials, which helps enhance device performance. By eliminating Pb° formation and passivating defects, the PeLEDs achieve an impressive external quantum efficiency (EQE) of 10.9% and up to 21.1% when integrating a light out-coupling structure.

The optical simulation of PeLEDs was done with SETFOS.

Kuo, H.-H., Kumar, S., Omongos, R. L., T. do Casal, M., Usteri, M. E., Wörle, M., Escudero, D., Shih, C.-J.,

Adv. Optical Mater. 2023, 2202519.

https://doi.org/10.1002/adom.202202519

Researchers have developed efficient phosphorescent emitters using abundant Au(III) complexes with asymmetric C^C^N ligands and carbazole moieties. The synthesized complexes exhibit shortened radiative lifetimes and high photoluminescence quantum yields, reaching over 93% in thin films. As a result, high-performance OLED devices demonstrate record-high external quantum efficiencies and current efficiencies, paving the way for the molecular design of anisotropic Au(III) emitters in next-generation optoelectronics.

The researchers quantified the horizontal dipole ratios in thin-films using the angular-dependent PL spectroscopy by fitting the experimental p-polarized (p-pol) angular PL intensity as a function of viewing angle with optical simulations using Setfos.

Tianqi Zhang,Pai Liu, Fangqing Zhao, Yangzhi Tan, Jiayun Sun, Xiangtian Xiao, Zhaojing Wang, Qingqian Wang, Fankai Zheng, Xiao Wei Sun, Dan Wu, Guichuan Xing and Kai Wang

Nanoscale Adv., 2023, 5, 385

https://doi.org/10.1039/d2na00705c

Researchers introduced an electric dipole layer in green InP QLEDs to enhance hole injection and balance carrier injection. This approach increased the carrier recombination rate, resulting in a high luminance of 52,730 cd m−2 and a 1.7 times EQE enhancement from 4.25% to 7.39%, paving the way for highly efficient green InP QLEDs.

Electrical simulations were performed with Setfos, while the constant or field-dependent electron and hole mobilities according to the Poole–Frenkel model were used in the simulations.

Researchers have made significant advancements in enhancing the efficiency of organic light-emitting diodes (OLEDs) by addressing two major light loss channels: substrate guided modes and evanescent modes. By micromachining hole patterns with specific characteristics onto the air/glass side of the OLED substrate, they achieved a 60% enhancement in light outcoupling efficiency (ηout) while reducing viewing angle dependence. This innovative approach prevents total internal reflection events and minimizes interference effects, improving OLEDs' general lighting applications.

In addition, a materials engineering approach was used to reduce losses to evanescent modes by employing π-conjugated polymers in the emissive layer. These polymers naturally emit TE-polarized radiation, reducing losses and enhancing ηout. The researchers developed a novel solution withdrawal coating (SWC) technique to simultaneously deposit the polymer film and control uniaxial orientation, resulting in highly efficient OLED displays with linearly polarized luminescence. This groundbreaking work paves the way for further advancements in the OLED technology, making it more efficient and versatile for various applications.

SETFOS was used to simulate the mode contributions within the OLED and optimize the dimensions of the glass patterns made at the air/substrate interface.

Jingwen Feng, Maocheng Jiang, Dong Li, Yuanming Zhang, Chen Pei, Li Zhou, Zhuo Chen, Yanzhao Li, Xinguo Li, and Xiaoguang Xu

The Journal of Physical Chemistry Letters 2023 14 (10), 2526-2532

https://doi.org/10.1021/acs.jpclett.3c00307

High-performance, eco-friendly heavy metal-free (HMF) quantum dot LEDs are vital for next-gen displays. ZnSeTe/ZnSe/ZnS blue QDs achieve adjustable energy levels & emission peaks, yielding a peak CE of 11.8 cd A−1. Optimizing chroma efficiency, these QLEDs offer 2.2x improvement over control devices.

SETFOS simulation software was utilized to assist in determining the optimal optical structure of the device, and we find that the emission intensity and peak position can be better matched in ZnSe:0.0385Te/ZnSe/ZnS-based QLED.

Huo, M.; Hu, Y.; Xue, Q.; Huang, J.; Xie, G.

Molecules 2023, 28, 2145.

https://doi.org/10.3390/molecules28052145

Organic/inorganic hybrid materials, like PVA and TTIP, show excellent optical properties for multilayer antireflection films. With a tunable refractive index & low haze, they achieve high transmittances up to 99.3%. Applied to perovskite solar cells, they boost efficiency from 16.57% to 17.25%.

The hybrid material/CA stack and the hybrid material/PMMA stack were simulated by Setfos.

Yun Hu, Jing-song Huang, Paul N. Stavrinou, Donal D. C. Bradley, Proc. SPIE 12314, Optoelectronic Devices and Integration XI,

123140O (20 December 2022); doi: 10.1117/12.2641624

Organic-oxide hybrid DBRs achieve high conductivity & light manipulation in organic optoelectronic devices. MoO3 doping increases TAPC conductivity by 10,000x with minimal refractive index change. Integrated OLEDs with bottom conductive DBRs demonstrate light regulation at low voltage.

The optical simulations of DBR and OLED devices were performed by using a commercially available SETFOS (Fluxim) program. The refractive index, extinction coefficient (k), photoluminescence (PL) spectrum of emissive layers and thickness of each layer were used as input parameters. Transfer matrix method (TMM) and Gaussian dipole distribution dipole emitter as source are used in simulation.

Aeberhard, U., Zeder, S.J. & Ruhstaller, B.

Opt Quant Electron 54, 617 (2022).

https://doi.org/10.1007/s11082-022-03791-9

The impact of photon recycling on the efciency of light extraction from metal halide perovskite light emitting diodes is quantifed using a novel modelling framework based on a detailed-balance compatible Green dyad approach. Analysis of photon modes contributing to internal emission and iterative evaluation of re-absorption and re-emission processes is performed for single perovskite layers in absence and presence of a metallic refector and under consideration of associated parasitic absorption losses. Finally, the approach is employed to characterize the emission characteristics of a realistic multilayer device stack in dependence of the emitter thickness.

The photon recycling simulation was performed with Setfos.

Kuo-Hsien Chou, Tun-Hao Chen, Xian-Qing Huang,a Chia-Sheng Huang, Chih-Hao Chang, Chien-Tien Chen and Jwo-Huei Jou

Mater. Adv., 2023,4, 1335-1344

DOI: 10.1039/d2ma00974a

Organic light-emitting diodes (OLEDs) are increasingly used in display technology and lighting, with a need for better electron-transporting materials (ETMs) for higher efficiency and longer lifetimes. Researchers synthesized four seven-member-ring-based ETMs, finding that using 2′,12-di(pyridin-4-yl)spiro[dibenzo[3,4:5,6]cyclohepta[1,2-b]pyridine-9,9′-fluorene] (DPP) as an ETM increased green OLED efficiency by 39% and device lifetime by 43% compared to 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBi).

The improvements were attributed to DPP's higher electron mobility and deeper highest occupied molecular orbital (HOMO) level. However, DPP was unsuitable for blue phosphorescent emitters, but another synthesized ETM, 4-(spiro[dibenzo[3,4:5,6]cyclohepta[1,2-b]pyridine-9,9′-fluoren]-12-yl)benzonitrile (PC), increased blue OLED efficiency by 46% compared to TPBi.

The recombination rate of the studied OLEDs were obtained by using electrical simulation software SETFOS.

Salem, M.S.; Shaker, A.; Abouelatta, M.; Saeed, A.

Polymers 2023, 15, 784.

https://doi.org/10.3390/polym15030784

Researchers have designed and analyzed perovskite/organic tandem solar cells (TSCs) using a full optoelectronic simulator (SETFOS).

A lead-free ASnI2Br perovskite top subcell is paired with a DPPEZnP-TBO:PC61BM heterojunction organic bottom subcell, based on previous experimental work. Calibration shows strong agreement between simulation and experimental data.

The optimized tandem cell achieves 14% efficiency with further improvements possible through concurrent optimization and defect reduction. This study provides valuable insights and directions for enhancing lead-free perovskite/organic TSC efficiency.

Pietro Caprioglio, Joel A. Smith, Robert D. J. Oliver, Akash Dasgupta, Saqlain Choudhary, Michael D. Farrar, Alexandra J. Ramadan, Yen-Hung Lin, M. Greyson Christoforo, James M. Ball, Jonas Diekmann, Jarla Thiesbrummel, Karl-Augustin Zaininger, Xinyi Shen, Michael B. Johnston, Dieter Neher, Martin Stolterfoht & Henry J. Snaith

Nat Commun 14, 932 (2023).

https://doi.org/10.1038/s41467-023-36141-8

Wide-gap perovskites suffers from Voc- and Jsc-deficit, but what's the reason and how to solve it?

Researchers from the groups of professors Henry J. Snaith and Martin Stolterfoht recently demonstrated starting from drift-diffusion simulation studies that a poor band-alignment with the electron transporting layer causes the Voc-deficit, while mobile ions obstacle the charge extraction causing Jsc losses. The voltage losses were solved by inducing the growth of a low-dimensional perovskite with a surface treatment based on guanidinium bromide (GuaBr) or imidazolium bromide (ImBr). To improve the charge extraction, they modified the hole-transporting layer applying an ionic interlayer (TEA-TFSI) or replaced it with self-assembled monolayer (SAM).

They used the simulation software Setfos from Fluxim AG to reveal that the hole-transporting layers enhance the charge extraction by inducing a stronger electric field at the interface with the perovskite.

Liu, Y., Yang, J., Mao, Z., Ma, D., Wang, Y., Zhao, J., Su, S.-J., Chi, Z.,

Adv. Optical Mater. 2023, 2201695

DOI: 10.1002/adom.202201695

The article reports on the development of three thermally-activated delayed fluorescence (TADF) molecules with different donor-acceptor (D-A) frameworks, namely D-A, D-A-D, and D-A-A. The TADF molecules were evaluated for their photophysical and electroluminescence properties. The study found that the TADF molecule with the D-A-A framework achieved the best performance in terms of external quantum efficiency due to its low energy gap between singlet and triplet, effective reverse intersystem crossing, high photoluminescence quantum yield, and horizontal dipole ratio. The study provides insights into the design of efficient TADF emitters.

P-polarized angle-dependent light emissions of CBP doped films were measured by Fluxim using Phelos. Refractive index of the materials was measured by MEL broadband spectroscopic Mueller matrix ellipsometer or extracted by Setfos database. The light out-coupling efficiency of devices was simulated by Setfos.

CS Appl. Mater. Interfaces 2023, 15, 1, 1652–1660

https://doi.org/10.1021/acsami.2c17960

The presence of spontaneous orientation polarization (SOP) in the electron transport layer (ETL) of organic light-emitting devices (OLEDs), induced by the alignment of polar molecules with permanent dipole moments (PDMs), can reduce device efficiency by quenching excitons.

This work quantitatively examines SOP formation in the ETL, considering the impact of film processing conditions and treating the vapor-deposited film as a supercooled glass. The results provide a framework to predict the SOP formation efficiency for polar materials and blends, and in situ measurements reveal that SOP-induced exciton-polaron quenching can be mitigated through optimized processing conditions, leading to improved OLED efficiency.

Optical Outcoupling Calculations. Light outcoupling efficiencies (ηoc) for OLEDs of interest were calculated using the simulation results obtained from Setfos. During the simulation, an isotropic dipole orientation was assumed, and optical constants measured via spectroscopic ellipsometry were used. The IQE for each device is calculated by dividing its ηEQE by its corresponding ηOC.

Fan, XC., Wang, K., Shi, YZ. et al.

Nat. Photon. (2023). https://doi.org/10.1038/s41566-022-01106-8

Researchers developed a new ultrapure green emitter called DBTN-2 for use in organic light-emitting diode (OLED) displays, which has a highly efficient operation due to the introduction of multiple carbazole moieties resulting in a high density of triplet states and a fast rate of reverse intersystem crossing.

An OLED using DBTN-2 as an emitter demonstrated a high photoluminescence quantum yield, strong horizontal dipole orientation, and excellent external quantum efficiency of 35.2% with suppressed efficiency roll-off, meeting commercial requirements for a green OLED display.

The obtained PL intensity angle-dependent patterns were analysed using Setfos with refractive index n, extinction coefficient k values of SF3-TRZ at 520 nm (peak wavelength of DBTN-2) as basic information for simulation.

Carl Degitz , Markus Schmid, Falk May, Jochen Pfister, Armin Auch, Wolfgang Brütting, and Wolfgang Wenzel

Chem. Mater. 2023, 35, 1, 295–303

https://doi.org/10.1021/acs.chemmater.2c03177

Due to their thin amourphous structure, unique electrical properties, and the associated variety of possible applications, OLEDs can now be found in smartphones, TVs, laptops, and wearables. While already big steps have been made in optimizing and understanding the properties influencing the external quantum efficiency (EQE), there is still room for improvement, especially when it comes to finding design principles for new emitter complexes. One contributer to the EQE here is the molecular orientation of the emitter in a given host matrix.

In this work the researchers study the viability of using molecular modeling approaches in sampling these emitter orientations for a set of already published homoleptic Ir carbene emitters and a set of emitter materials synthesized at Merck KGaA, Darmstadt, Germany, comprising both homoleptic and heteroleptic Ir(ppy)3 derivatives.

They combined these simulations with different measurements for the orientation parameter and EQE, all performed with the same material stack under the same conditions. The research team observed a good agreement between simulation and experiment and found that the horizontal orientation of emitter molecules seems to be the main factor contributing to a higher EQE.

The Setfos Optics module was used to calculate the maximum possible EQE for emitter.

Yun Hu, Jing-song Huang, Paul Stavrinou, Donal D. C. Bradley

Proc. of SPIE Vol. 12314 123140O-2, 2023

Non-metallic mirror, such as semiconductor distributed Bragg reflectors (DBRs), has been widely integrated in the structure of optoelectronic devices.

However, constructing conductive DBR in organic optoelectronic device is still scarce, because of the incompatibility of high-temperature processes in the preparation of inorganic DBR.

Herein, it is confirmed that organic-oxide hybrid DBR can achieve high conductivity and light manipulation. When thermal evaporated material MoO3 is doped into organic material (1,1-bis[4-[N,N-di(p-tolyl)amino]phenyl]cyclohexane, TAPC), the conductivity of TAPC can be increased by ten thousand times with very small refractive index change.

It is shown that 8.5 pairs DBR at 460 nm has a reflectivity of about 95%, and the driving voltage is 8.2 V at the current density of 100 mA cm-2. Then, a transparent organic light-emitting diode with integrated bottom conductive DBR are fabricated to confirm the functionality of light regulation.

The results confirm that integrated optoelectronic devices with DBR as reflector can be achieved with low operating voltage.

The optical simulations of DBR and OLED devices were performed by using a commercially available SETFOS (Fluxim) software. The refractive index, extinction coefficient (k), photoluminescence (PL) spectrum of emissive layers and thickness of each layer were used as input parameters. Transfer matrix method (TMM) and Gaussian dipole distribution dipole emitter as source are used in simulation.

Li, Y., Wu, X., Zuo, G., Wang, Y., Liu, X., Ma, Y., Li, B., Zhu, X.-H., Wu, H., Qing, J., Hou, L., Cai, W.,

Adv. Funct. Mater. 2022, 2209728.

https://doi.org/10.1002/adfm.202209728

Efficient electron transport layer (ETL) based on a novel n-n heterojunction arrangement for organic photovoltaics (OPV).

The group of Whanzu Cai at the Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials stacked an n-type conjugated film (PNDIT-F3N) with an n-type small molecule film (Phen-NaDPO) achieving a water-fall like alignment of electron transport energy levels. Devices with the n-n heterojunction ETL showed performance increase of up to 30% compared to control devices based on the isolated PNDIT-F3N or Phen-NaDPO ETLs.

They used the characterization tool Paios to investigate the charge extraction and recombination lifetimes with transient photocurrent (TPC) and transient photovoltage (TPV) measurements, respectively. Both extraction and recombination lifetimes improved by up to 100% for the devices with the n-n heterojunction compared to Phen-NaDPO alone.

van der Pol, T.P.A., Datta, K., Wienk, M.M. and Janssen,

R.A.J. (2022), Sol. RRL, 6: 2200872.

https://doi.org/10.1002/solr.202200872

A modeling approach is developed to correct outcoupled electroluminescence spectra in thin-film organic and perovskite solar cells. The approach takes into account self-absorption, cavity effects, and nonhomogeneous emission profile to yield intrinsic spectrum. The impact of these effects is studied for various device parameters to uncover trends and provide guidelines for a large set of devices.

Optical Modeling: The simulation procedure used here was based on Dyson et al. where the outcoupled spectrum is calculated using Setfos for a 1 nm emitter layer located in the active layer

Rahman, Md Abdur, Kim, Dong Kyu, Lee, Jong-Kwon and Byun, Ji Young.

Nanophotonics, vol. 11, no. 21, 2022, pp. 4855-4868.

https://doi.org/10.1515/nanoph-2022-0522

Structural colors with tunable properties have extensive applications in surface decoration, arts, absorbers, and optical filters.

CrON/Si3N4/Metal structures show promise for generating vivid structural colors with tunable properties and strong light absorption. Replacing top metallic layer with lossy dielectric prevents degradation from abrasiveness/oxidation. Theoretical and experimental data support these structures' durability and color generation via interference effect and absorption rate

The absorption of each layer and phase shift were calculated using Setfos.

Markus Regnat, Chang-Ki Moon, Sandra Jenatsch, Beat Ruhstaller, Kurt P. Pernstich,

Organic Electronics, Volume 108, 2022, 106570, ISSN 1566-1199,

https://doi.org/10.1016/j.orgel.2022.106570.

Highlights

• Increased driving voltage after prolonged operation.

• Radiant flux remained constant, so an electrical model is sufficient.

• Using multiple measurement methods, determine reliable model parameters.

• Sensitivity analysis reveals the origin of the increased driving voltage.

• Hole traps in TAPC are the main cause of the increased driving voltage.

Fluxim’s all-in-one measurement system, Paios, equipped with a temperature module and a photomultiplier from Hamamatsu (H11526 Series), was used to measure OLED characteristics.

Fluxim's Characterization Suite software (version 4.3) was used to analyze the obtained data, which included the Setfos-Paios-Integration feature for performing model parameter optimizations for fitting the measured data.

Weitz, P., Le Corre, V. M., Du, X., Forberich, K., Deibel, C., Brabec, C. J., Heumüller, T.,

Adv. Energy Mater. 2022, 2202564.

https://doi.org/10.1002/aenm.202202564

A method for organic solar cell (OSC) stability testing is presented that aims to provide more unique insight into the causes of degradation patterns of OSCs. The method involves using monochromatic light at high irradiation doses to accelerate isolated degradation mechanisms while monitoring the device with a series of in-situ steady-state and transient electrical measurements.

The experimental results are accompanied by drift-diffusion simulations to localize degradation pathways. PM6:Y6-based OSCs are tested, which are known to show a rather broad range of lifetimes as a function of device architecture, material batches, or degradation conditions. The experiments reveal a degradation mechanism that causes an increased trap-state density inside the PM6:Y6 layer.

The transient simulations suggest that these states are formed at or around the interface between the PM6:Y6 and the electron transport layer. Furthermore, the surprisingly dominant impact of the illuminating wavelength on the degradation pattern is evidenced.

Lastly, the degradation rate of the devices scales linearly with light intensity, making high intensity and spectrally selective degradation the most promising way to accelerate stability testing for the faster development of stable OSCs.

To localize a mechanism inside the device architecture, the commercial drift-diffusion module of the simulation software Setfos was used.

Cho, H., Joo, C. W., Kwon, B.-H., Kang, C., Choi, S., and Sin, J. W., ETRI Journal (2022), 1– 9.

doi.org/10.4218/etrij.2022-0236

Abstract

The optical properties of the materials composing organic light-emitting diodes (OLEDs) are considered when designing the optical structure of OLEDs. Optical design is related to the optical properties, such as the efficiency, emission spectra, and color coordinates of OLED devices because of the microcavity effect in top-emitting OLEDs.

In this study, the properties of top-emitting blue OLEDs were optimized by adjusting the thicknesses of the thin metal layer and capping layer (CPL). Deep blue emission was achieved in an OLED structure with a second cavity length, even when the transmittance of the thin metal layer was high.

The thin metal film thickness ranges applicable to OLEDs with a second microcavity structure are wide. Instead, the thickness of the thin metal layer determines the optimized thickness of the CPL for high efficiency.

A thinner metal layer means that higher efficiency can be obtained in OLED devices with a second microcavity structure. In addition, OLEDs with a thinner metal layer showed less color change as a function of the viewing angle.

Setfos was used to perform the optical simulations and to optimize the OLED stack design.

F. Didier, P. Alastuey, M. Tirado, M. Odorico, X. Deschanels, G. Toquer,

Thin Solid Films, Volume 764, 2023, 139614, ISSN 0040-6090,

doi.org/10.1016/j.tsf.2022.139614.

ABSTRACT

Carbon nanotubes (CNTs), deposited by electrophoretic deposition (EPD), are investigated as selective solar absorbers. First, various kinds of CNTs with different aspect ratios, are dispersed by ultrasound in an aqueous solution of pyrocatechol violet (PV). PV couples to the CNT’s outer walls via π-π stacking interactions and acts as a dispersing agent as well as a charging agent. PV adsorption isotherms on CNT combined with N2 physisorption isotherms are performed to optimize the CNT/PV ratio. In this way, Zeta potentials up to -40 mV are obtained for the dispersed CNTs, which are deposited on platinized silicon wafers by EPD, forming a film. The EPD kinetics are then investigated as a function of the applied electric field (in the 8–20 V cm− 1 range) and are explained through a Sarkar & Nicholson model type. X-ray reflectivity is performed to characterize the density around 1.3 g cm− 3 , and film cohesion is probed by nanoindentation coupled to atomic force microscopy images. The hemispherical reflectance of the samples is measured by spectrophotometers equipped with an integrating sphere, and following from spectra, the absorptance (α) and emittance (ԑ) are calculated. The selectivity of the deposits, based on α and ԑ values, is then discussed as a function of the applied electric field and the coating thickness.

Single-walled CNT deposits, at best, are found to have a solar absorptance of 0.91 and thermal emission of 0.05. Thermal annealing experiments reveal that the coatings could withstand up to 300 ◦C while sustaining selective properties and losing only 21% of the initial yield.

The researchers used Setfos to simulate the absorbed radiation and thermal emission of their films.

Hu, D., Tang, H., Karuthedath, S., Chen, Q., Chen, S., Khan, J. I., Liu, H., Yang, Q., Gorenflot, J., Petoukhoff, C. E., Duan, T., Lu, X., Laquai, F., Lu, S.,

Adv. Funct. Mater. 2022, 2211873.

doi.org/10.1002/adfm.202211873

Abstract

The commercial viability of all-small-molecule (ASM) organic solar cells (OSCs) requires high efficiency, long-term stability, and low-cost production.

However, satisfying all these factors at the same time remains highly challenging. Herein, a volatile solid additive, namely, 1,8-dichloronaphthalene (DCN) is demonstrated to simultaneously enhance the power conversion efficiency (PCE) and the storage, thermal as well as photo stabilities of oligothiophene ASM-OSCs with concise and low-cost syntheses.

The improved PCEs are mainly due to the DCN-induced morphology control with improved exciton dissociation and reduced non-geminate recombination. Notably, the PCE of 16.0% stands as the best value for oligothiophene ASM-OSCs and is among the top values for all types of binary ASM-OSCs. In addition, devices incorporating DCN have shown remarkable long-term stability, retaining over 90% of their initial PCE after dark storage aging of 3000 h and thermal or light stressing of 500 h.

The findings demonstrate that the volatile-solid-additive strategy can be a simple yet effective method of delivering highly efficient and stable oligothiophene ASM-OSCs with excellent commercial viability.

The 1D numerical drift-diffusion module of Setfos was used to simulate the O-ASM-OSCs device J–V characteristics.

Tasaki, S, Nishimura, K, Toyoshima, H, Masuda, T, Nakamura, M, Nakano, Y, et al.

J Soc Inf Display. 2022; 30( 5): 441– 451.

https://doi.org/10.1002/jsid.1127

The bilayer structure for an emitting layer (EML) was developed to improve performances of a fluorescence blue organic light emitting diode.

By functionally separating the EML into the charge recombination and the triplet–triplet fusion (TTF) zone, we successfully suppressed the quenching of triplet excitons by excess carriers to make more TTF efficient and the local degradation within the EML to make the lifetime longer.

In the bottom emission device with the bilayer EML, 12% of external quantum efficiency (EQE) and 450 h of LT95 were achieved. Furthermore, we achieved over 14% of EQE by optimizing the material combinations.

To estimate the emission ratio from BH1 and BH2, optical simulation by Setfos was conducted at 10 mA/cm2.20

Lee, H.-D., Jang, H. J., Baek, J. H., Kim, J.-J., Choi, H. C., Kim, J.-M., Lee, J. Y.

Adv. Optical Mater. 2022, 2202109.

doi.org/10.1002/adom.202202109

Abstract

Control of the molecular orientation is an effective approach to enhance the performance of organic light-emitting diodes. This study examines the molecular dipole orientation of hole transport materials depending on the deposition step and the consecutive effect on the transition dipole orientation of the emitting dopant.

In contrast to other reference materials, 4,4′,4′′-tris(carbazole-9-yl)triphenylamine (TCTA) shows a preferred orientation only in the continuously deposited films that is dependent on the film thickness. The horizontal dipole orientation ratio of the emitting dopant deposited on the TCTA is improved by the alignment of TCTA molecules.

The power efficiency of the device produced from the above materials is increased from 28.9 to 34.4 lm W−1 owing to the dual enhancement of the hole mobility of TCTA and the horizontal dipole orientation ratio of the emitting dopant. The molecular orientation of the charge transport layer contributes to charge transport in the layer and the molecular orientation of the adjacent emitting layer.

The optical simulation for determining the horizontal dipole ratio was performed using Setfos.

Yun-Jie Lin, Chia-Sheng Huang, Pei-Chung Tsai, Yu-Lun Hsiao, Cheng-Yu Chen, and Jwo-Huei Jou

ACS Applied Materials & Interfaces Article ASAP

DOI: 10.1021/acsami.2c18275

Abstract

Aluminum has been extensively used as a conductor material in numerous electronic devices, including solar cells, light-emitting diodes (LEDs), organic LEDs (OLEDs), and thin-film transistors. However, its spiking surface and easy electromigration have limited its performance.

To overcome this, a trace amount of nonprecious copper dopant has been proven effective in enhancing device reliability. Nevertheless, a comprehensive investigation regarding the effect of copper doping on the morphology at the aluminum conductor–organic interface is yet to be done. We had hence fabricated a series of green OLED devices to probe how copper doping affected the aluminum conductor, morphologically and electrically, and the corresponding device’s efficiency and lifetime performance.

Electrical simulation showing the effect of the cathode work function on the charge density distribution of the studied green OLED devices was performed using Setfos.

Tommaso Marcato, Frank Krumeich, and Chih-Jen Shih

ACS Nano 2022 16 (11), 18459-18471

DOI: 10.1021/acsnano.2c06600

Tuning the transition dipole moment (TDM) orientation in low-dimensional semiconductors is of fundamental and practical interest, as it enables high-efficiency nanophotonics and light-emitting diodes. However, despite recent progress in nanomaterials physics and chemistry, material systems that allow continuous tuning of the TDM orientation remain rare.

Here, combining k-space photoluminescence spectroscopy and multiscale modeling, we demonstrate that the TDM orientation in lead halide perovskite (LHP) nanoplatelet (NPL) solids is largely confinement-tunable through the NPL geometry that regulates the anisotropy of Bloch states, dielectric confinement, and exciton fine structure.

The experimental data were evaluated with the software Setfos provided by Fluxim.

The angle-dependent PL of the NPL film was characterized using the commercial instrument Phelos (Fluxim Inc.) equipped with a spectrometer, a linear polarizer, and a cylindrical macro extractor lens.

Luo, Y., Zhang, K., Ding, Z. et al.

Nat Commun 13, 6892 (2022).

https://doi.org/10.1038/s41467-022-34573-2

The harvesting of ‘hot’ triplet excitons through high-lying reverse intersystem crossing mechanism has emerged as a hot research issue in the field of organic light-emitting diodes.

However, if high-lying reverse intersystem crossing materials lack the capability to convert ‘cold’ T1 excitons into singlet ones, the actual maximum exciton utilization efficiency would generally deviate from 100%.

Herein, through comparative studies on two naphthalimide-based compounds CzNI and TPANI, we revealed that the ‘cold’ T1 excitons in high-lying reverse intersystem crossing materials can be utilized effectively through the triplet-triplet annihilation-mediated high-lying reverse intersystem crossing process if they possess certain triplet-triplet upconversion capability.

Angle-dependent photoluminescence was measured to obtain the horizontal dipole ratio (HDR, Θ//) of the light emission molecules in neat film state. p-polarized angle-dependent light emissions of films were measured by Fluxim. The HDR of thin films and light out-coupling efficiency of devices were then simulated by Setfos.

Liu, G., Li, Z., Hu, X. et al.

Nat. Photon. 16, 876–883 (2022).

https://doi.org/10.1038/s41566-022-01084-x

Organic light-emitting diodes (OLEDs) with thick carrier transport layers are desirable for high production yields of OLED-based displays and lighting; however, high operating voltages are inevitably introduced to thick OLEDs due to the low carrier mobilities of organics.

The associated Joule heating will also induce structural defects and lower operational stabilities. Here, the researchers demonstrate highly efficient and stable OLEDs with thicknesses of over 1 μm and low operating voltages.

The researchers used the advanced simulation software Setfos.

Hu, Y.X., Miao, J., Hua, T. et al.

Nat. Photon. 16, 803–810 (2022).

https://doi.org/10.1038/s41566-022-01083-y

Organic light emitters based on multiresonance-induced thermally activated delayed fluorescent materials have great potential for realizing efficient, narrowband organic light-emitting diodes (OLEDs).

However, at high brightness operation, efficiency roll-off attributed to the slow reverse intersystem crossing (RISC) process hinders the use of multiresonance-induced thermally activated delayed fluorescent materials in practical applications. In this paper, the researchers report a heavy-atom incorporating emitter, BNSeSe, which is based on a selenium-integrated boron–nitrogen skeleton and exhibits 100% photoluminescence quantum yield and a high RISC rate (kRISC) of 2.0 × 106 s−1.

The corresponding green OLEDs exhibit excellent external quantum efficiencies of up to 36.8% and ultra-low roll-off character at high brightnesses (with very small roll-off values of 2.8% and 14.9% at 1,000 cd m−2 and 10,000 cd m−2, respectively).

The optical simulation of OLED devices was performed using Setfos. The input parameters include refractive index value, extinction coefficient, thickness of each layer values (all measured by ellipsometry), as well as photoluminescence spectrum of the emitting layer.

Abhijeet Choudhury, Mangey Ram Nagar, Luke The, Yun-Jie Lin, Yu-Hong Liang, Sun-Zen Chen, Jwo-Huei Jou,

Organic Electronics, Volume 111, 2022, 106668, ISSN 1566-1199,

https://doi.org/10.1016/j.orgel.2022.106668

High-efficiency organic light-emitting diodes (LEDs) can be achieved by employing efficiency-effective materials coupling with suitable device architectures.

Among them, there have been numerous hole-injection and -transport materials reported, but having issues of high-cost, solution-process feasibility, and toxic solvent involvement. In this paper the researchers demonstrate a low-cost solution-processable nanocrystalline copper iodide (CuI) as a hole-injection and -transport material for the fabrication of high-efficiency organic LED.

Outcoupling efficiency is a crucial factor that help in the OLEDs efficiency enhancement. To measure the outcoupling efficiency of OLEDs, which has amorphous CuI and nanocrystalline CuI as HIL/HTL, optical simulation was performed using SETFOS. For the optical simulation, optical parameter, i.e. refractive index, of all functional layers were provided in the software package.

M. Diethelm, A. Devižis, W.-H. Hu, T. Zhang, R. Furrer, C. Vael, S. Jenatsch, F. Nüesch, R. Hany

Adv. Funct. Mater. 2022, 32, 2203643. https://doi.org/10.1002/adfm.202203643

This research investigates the impact of electron and hole traps on the performance and lifespan of polymer light-emitting electrochemical cells (PLECs). The study aims to identify and analyze the role of these traps in PLECs, drawing parallels with their known impact on polymer light-emitting diodes (PLEDs).

The researchers fabricated PLECs using a super yellow (SY) polymer as the emitting material and employed various experimental techniques, including electrical driving and breaks, light irradiation, and long-term absorption and capacitance measurements. Optical and electrical simulations using Setfos provided further insights into device behavior.

The findings reveal that electron traps in PLECs share similar characteristics with those in PLEDs, suggesting a common origin in the semiconducting polymer. Notably, the study identifies two types of hole traps in PLECs: one type present in the intrinsic region, mirroring PLED behavior, and another type forming at the interface of the intrinsic and p-doped regions, specific to the PLEC architecture.

This research highlights the significant role of charge traps in limiting PLEC performance and longevity. The findings emphasize the need for strategies beyond conventional approaches to enhance PLEC stability, urging a focus on addressing the fundamental limitations posed by charge traps within the light-emitting polymer itself.

How Setfos Was Used

Setfos was used to perform optical and electrical simulations of the PLEC devices to better understand their properties, such as luminance versus emitter position.

How Paios Was Used

Paios was used to perform several different types of measurements on the PLEC devices:

Impedance measurements: Specifically, impedance measurements at 0 V with an alternating 70 mV signal were taken to determine the capacitance transients of the devices.

Current and light intensity transient measurements: The Paios measurement system was also used to measure how the current and light intensity changed over time. The light intensity was measured by using a photodiode to measure the photovoltage, and the relationship between the measured photovoltage and the corresponding radiance/luminance is explained in a different source.

How Phelos Was Used

Phelos was used to take angular-dependent electroluminescence (EL) measurements of the PLEC devices.

Ahmer A.B. Baloch, Omar Albadwawi, Badreyya AlShehhi, Vivian Alberts,

Energy Reports, Volume 8, Supplement 16, 2022,

ISSN 2352-4847,

https://doi.org/10.1016/j.egyr.2022.10.215

What is the worldwide performance of silicon/perovskite solar cells compared to the respective single-junctions?

That is the question that the group of Vivian Alberts from the Research and Development Center of the Dubai Electricity and Water Authority answered by simulating the energy yield and cell temperature depending on the geographical location.

Considering a perovskite solar cell with a bandgap of 1.7eV, tandem cells generate on average 26.7% more energy than silicon solar cells, while dissipating less heat thanks to the higher electrical efficiency. The optimal latitude for tandem performance in the 45◦N to 45◦S range.

With the simulation software Setfos from Fluxim AG they could estimate the theoretical efficiency limit of the tandem device under standard testing conditions (STC) using detailed balance analysis.

Yutaka Noguchi, Kaito Ninomiya, and Katsuya Sato

The Journal of Physical Chemistry C Article ASAP

DOI: 10.1021/acs.jpcc.2c05871

Understanding the charge distributions in the vicinity of the emission layer (EML) of an organic light-emitting diode (OLED) is crucial for improving device performance.

In this paper the researchers from Meiji University, Japan propose a simple but powerful technique for investigating the correlations between the dynamics of charge carriers and excitons. This technique (DCM-PL) is based on displacement current measurement (DCM) with simultaneous observation of the photoluminescence (PL) intensity.

By applying this technique to metal−insulator−semiconductor (MIS) devices incorporating a partial stack of a tris(2-phenylpyridine) iridium (III) [Ir(ppy)3]-based organic light-emitting diode (OLED), they were able to investigate the hole accumulation behavior and the corresponding PL losses due to exciton-polaron quenching (EPQ).

Remarkably, the DCM-PL characteristics revealed that the polarity of the host material in the emission layer modifies the chargecarrier dynamics and EPQ properties. The results contribute to the optimization of OLED device performance, since EPQ is a key process involved in efficiency roll-off and device degradation.

The DCM curves for the CBP and TPBi host devices, respectively, were calculated using Setfos 5.2.

Liu, G., Li, Z., Hu, X. et al.

Nature Photonics. 24 Oct. 2022

doi.org/10.1038/s41566-022-01084-x

Organic light-emitting diodes (OLEDs) with thick carrier transport layers are desirable for high production yields of OLED-based displays and lighting; however, high operating voltages are inevitably introduced to thick OLEDs due to the low carrier mobilities of organics.

The associated Joule heating will also induce structural defects and lower operational stabilities. Here the research team led by demonstrate highly efficient and stable OLEDs with thicknesses of over 1 μm and low operating voltages.

The p-polarized emitted light fittings were performed with the Setfos software38 to model a quartz/emitting layer (20 nm)/air based on their corresponding refractive index and emission wavelength.

Kunsik An, Chaewon Kim, Kwan Hyun Cho, Seunghwan Bae, Bo Kyung Cha, Kyung-Tae Kang,

Organic Electronics, Volume 100, 2022, 106384

doi.org/10.1016/j.orgel.2021.106384

An X-ray detector system was fabricated with an organic small molecule photodetector and a terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) scintillating screen. Though the microsphere cluster structure of the Gd2O2S film had advantage in low material cost, wavelength matching to the proper photodetector is challenging due to its scintillating performance property in the relatively narrow emission spectrum range.

This work, including the spectral tuning using the strong microcavity effect and X-ray detection for medical applications, will provide new insights for the further development of OPDs.

The optical calculation of the absorption spectra was carried out using SETFOS. The optical constants n (refractive index) and k (absorption index) were obtained from the software.

Sandheep Ravishankar, Zhifa Liu, Uwe Rau, and Thomas Kirchartz

PRX Energy 1, 013003 – Published 7 April 2022

Capacitance methods, such as capacitance-voltage-frequency measurements, Mott-Schottky analysis, and thermal-admittance spectroscopy measurements, are powerful tools to obtain important parameters of the solar cell, such as doping and defect densities, built-in voltages, and activation energies.

However, the validity of these analyses assumes that the capacitance response originates solely from the absorber layer.

Here, the authors demonstrate that this assumption is not valid for perovskite solar cells, since the thin and low-mobility selective-contact layers significantly contribute to the measured capacitance. Using a combination of drift-diffusion simulations and analytical modeling, they develop guidelines for the measurement of doping and defect densities, built-in voltages, and activation energies from these capacitance methods. These guidelines can be applied to any photovoltaic technology that incorporates low-conductivity charge-transport layers in addition to the absorber layer.

Simulation with ions was performed using Setfos.

Han-un Park, Seong Keun Kim, Raju Lampande, Jang Hyuk Kwon

Organic Electronics, Volume 105, 2022, 106496, ISSN 1566-1199,

https://doi.org/10.1016/j.orgel.2022.106496.

Here, the researchers report surface plasmon (SP) loss improved top-emitting organic light emitting diodes (TEOLEDs) by applying their unique cathode unit structure. Generally, the TEOLED has high optical loss portion of SP mode compared to the bottom emitting OLED and it causes low out-coupling efficiency in the TEOLED. Commonly used TEOLED structure uses Ag:Mg (10:1, 22 nm) cathode with high refractive index single capping layer, which has high optical loss portion of SP mode. To reduce SP mode loss in the TEOLED, we applied thin Ag:Mg (10:1, 12 nm) cathode with multi-capping layer. Our cathode unit reduces 55% of SP loss and enhances about 20% efficiency.

Their approach to enhance out-coupling efficiency will be useful to make high efficiency TEOLEDs.

The optical simulations of TEOLEDs were performed using Setfos. The refractive index, extinction coefficient, photoluminescence spectrum of emissive layer and thickness of each layer were used as input parameters.

Guanding Mei , Weigao Wang, Dan Wu, Philip Anthony Surman, Kai Wang , Wallace C. H. Choy , Xiaochuan Yang, Wenwei Xu, and Xiao Wei Sun

IEEE PHOTONICS JOURNAL, VOL. 14, NO. 2, APRIL 2022

https://ieeexplore.ieee.org/document/9735367

Full-color display is a primary challenge for the commercialization of quantum dots (QDs). In this study, we utilize the spectral narrowing phenomenon of microcavities to fabricate the red, green and blue quantum dot light-emitting diodes (QLEDs) with a single QD layer.

Because QD can be approximated as a point dipole source, the optical simulations are based on the dipole model and were performed by Setfos.

Maki Hiraoka, Nobuyuki Ishida, Akio Matsushita, Ryusuke Uchida, Takeyuki Sekimoto, Teruaki Yamamoto, Taisuke Matsui, Yukihiro Kaneko, Kenjiro Miyano, Masatoshi Yanagida, and Yasuhiro Shirai

CS Appl. Energy Mater. 2022, 5, 4, 4232–4239

doi/10.1021/acsaem.1c03747

Kelvin probe force microscopy has been employed to monitor the cross-sectional potential profile in lead-halide perovskite photovoltaic cells. From systematic investigations on many devices under varying bias voltage and light illumination conditions, we are able to deduce quantitative profile features with low noise that allows us to compare the local electronic properties in the working devices against numerical calculations.

The research team applied this technique to devices before and after degradation. Through the profile change before and after, we located the degraded components and inferred the source of the loss of the performance.

Setfos was used to simulate the photovoltaic actions of the device.

Palepu Ashok, Jay Chandra Dhar

2022 International Conference for Advancement in Technology (ICONAT), 2022, pp. 1-6,

doi: 10.1109/ICONAT53423.2022.9725852.

Here the researchers designed an HTL free photo detector with ZnO as an electron transport layer (ETL) fabricated using RF sputtering and the perovskite material CH3NH3PbI3 as a light absorbing material deposited using two-step spin coating method.

The performance of the device is modelled by using SETFOS software with the impedance spectroscopy technique by changing different metal electrodes like, Ag, Au, Pd and Pt. Among all, the Pt electrode showed high current density (18.6914 mA/cm^2), high fill factor (0.558) and maximum power conversion efficiency (18.5%).

Rossa Mac Ciarnáin*, Hin Wai Mo, Kaori Nagayoshi, Hiroshi Fujimoto, Kentaro Harada, Robert Gehlhaar, Tung Huei Ke, Paul Heremans & Chihaya Adachi*

Advanced Materials (2022)

https://onlinelibrary.wiley.com/doi/full/10.1002/adma.202201409

An accessible method based on a single emission spectrum that enables emission zone measurements with sub-second time resolution in an organic light-emitting diode (OLEDs) is shown. A procedure is introduced to study and control the emission zone of an LED system and correlate it with device performance. A thermally activated delayed fluorescence organic LED emission zone is experimentally measured over all luminescing current densities while varying the device structure and while aging.

Emmanuel O. Afolayan , Ibrahim Dursun , Chao Lang, Evgeny Pakhomenko ,Marina Kondakova, Michael Boroson , Michael Hickner, Russell J. Holmes , and Noel C. Giebink

Physical Review Applied 17, LO51002 (2022)

DOI: 10.1103/PhysRevApplied.17.L051002

Spontaneous orientational polarization (SOP) in the electron-transport layer (ETL) of OLEDs is increasingly recognized as a key factor influencing their performance. The authors shows that SOP is dramatically reduced in the common electron-transport material 2,2,2- (1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) by coevaporating it together with medium-density polyethylene. Eliminating SOP from the ETL of blue fluorescent OLEDs reduces their operating voltage by 0.5 V, increases their external quantum efficiency (EQE) by 30%, and leads to a threefold increase in device lifetime.

Wei-Hsu Hu, Camilla Vael, Matthias Diethelm, Karen Strassel, Surendra B. Anantharaman, Abdessalem Aribia, Marco Cremona, Sandra Jenatsch, Frank Nüesch, and Roland Hany

Adv. Optical Mater. 2022, 2200695

DOI: 10.1002/adom.202200695

Organic upconversion devices (OUCs) consist of an organic infrared photodetector and an organic visible light-emitting diode (OLED), connected in series. OUCs convert photons from the infrared to the visible and are of use in applications such as process control or imaging.

Many applications require a fast OUC response speed, namely the ability to accurately detect in the visible a rapidly changing infrared signal.

Here, high image-contrast, narrowband OUCs are reported that convert near-infrared (NIR) light at 980 and 976 nm with a full-width at half maximum of 130 nm into visible light. Transient photocurrent measurements show that the response speed decreases when lowering the NIR light intensity. This is contrary to conventional organic photodetectors that show the opposite speed-versus-light trend.

It is further found that the response speed increases (when using a phosphorescent OLED) or decreases (for a fluorescent OLED) when increasing the driving voltage.

To understand these surprising results, an analysis by numerical simulation is conducted. Results show that the response speed behavior is primarily determined by the electron mobility in the OLED. It is proposed that the low electron drift velocity in the emitter layer sets a fundamental limit to the response speed of OUCs.

Optical and electrical simulations were performed with Setfos 5.2

Camilla Vael, Sandra Jenatsch, Simon Züfle, Frank Nüesch, and Beat Ruhstaller

Journal of Applied Physics 131, 205702 (2022)

doi.org/10.1063/5.0088426

Simplified physical models are insufficient to describe the transient current after thermal stimulation in organic semiconductors. This is a recent finding from the group of Beat Ruhstaller. Drift-diffusion simulations obtained with the simulation software Setfos revealed the shortcomings of the physical models.

Simulations modeling is more powerful than analytical approaches for the interpretation of experimental data by accounting for non-ideal properties like exciton splitting and non-homogenous trap densities.

Matthias Diethelm, Michael Bauer, Wei-Hsu Hu, Camilla Vael, Sandra Jenatsch

Adv. Funct. Mater. 2022, 2106185

DOI: 10.1002/adfm.202106185

In this paper the researchers investigate electron trap dynamics in SY PLEDs and discover a recovery feature of the traps during stress interruption. Formation of this trap states takes several minutes. Same behaviour was found for P3HT, MEH-PPV.

The optical and electrical characterization tool Paios was used to stress the PLED and investigate trap dynamics with/without light bias. Additionally TEL experiments show an overshoot if the break time between stressing is extended. Transient Setfos simulations for fast trap dynamics and steady-state voltage depending on Nt.

Soobin Sim, Jinha Ryu, Dae Hyun Ahn, Hyunsu Cho, Chan-mo Kang, Jin-Wook Shin, Chul Woong Joo, Gi Heon Kim, Chun-Won Byun, Nam Sung Cho, Hyoc Min Youn, Young Jae An, Jin Sun Kim, Hanyung Jung, and Hyunkoo Lee,

Opt. Express 30, 24155-24165 (2022)

doi.org/10.1364/OE.463095

Herein, the color gamut change by optical crosstalk between sub-pixels in high-resolution full-color organic light-emitting diode (OLED) microdisplays was numerically investigated. The color gamut of the OLED microdisplay decreased dramatically as the pixel density of the panel increased from 100 pixels per inch (PPI) to 3000 PPI.

Both Setfos and Laoss were used by the research team to perform optical simulations. To conduct the optical crosstalk simulation, the EL spectra was simulated using Setfos and the simulated EL spectra were well matched with the measured EL spectra. The transmittances of the R and G CFs provided by Laoss.

Tom P. A. van der Pol, Kunal Datta, Martijn M. Wienk, and René A. J. Janssen

Adv. Optical Mater. 2022, 2102557

doi.org/10.1002/adom.202102557

Photoluminescence (PL) helps you determine material properties and dynamic effects in #perovskite devices. But it is not easy to interpret PL spectra of #perovskites and get to the intrinsic material properties. This work is showing you how to do it.

The group of Prof. Rene Janssen at the Eindhoven University of Technology developed an optical model to quantify the intrinsic PL of a perovskite film and determine the influence of the extrinsic factors on the measured PL. The model is based on film thickness, refractive index, extinction coefficient, and carrier diffusion length as input parameters. The authors concluded that the largest mismatch between intrinsic and measured PL is observed for materials with a long diffusion length (>0.5um) and a layer thickness of >300nm.

The simulation software Setfos was instrumental in calculating an accurate emission spectrum to quantify the intrinsic PL for the perovskite. The simulation uses the real nk spectra of the materials and layer thickness as an input, which is the key to resolving the optical system.

The description you find in this paper can be used as a protocol to analyze your PL data on perovskite films.

Sudhir Kumar, Tommaso Marcato, Frank Krumeich, Yen-Ting Li, Yu-Cheng Chiu and Chih-Jen Shih

Nat Commun. (2022), 13, 2106

https://www.nature.com/articles/s41467-022-29812-5

The intrinsic light outcoupling efficiency of quantum dots remains considerably lower than the organic counterpart.

The authors, using the colloidal lead halide perovskite anisotropic nanocrystals (ANCs) as a model system, report a directed self-assembly approach to form an anisotropic nanocrystal superlattice of perovskite nanocrystals. The emission polarization in individual ANCs rescales the radiation from horizontal and vertical transition dipoles, effectively resulting in preferentially horizontal TDM orientation. The optimized single-junction QD LEDs showed peak external quantum efficiency of up to 24.96%, comparable to state-of-the-art organic LEDs.

Brinkmann, K.O., Becker, T., Zimmermann, F. et al.

Nature 604, 280–286 (2022).

doi.org/10.1038/s41586-022-04455-0

In this Nature paper the research team reached a new outstanding certified efficiency record of 23.1% with a two-terminal perovskite/organic solar cell.

Thanks to an ALD-deposited InOx interconnection layer, the current between the two subcells is perfectly matched at 14.1 mA/cm2. The high Voc of 2.15 V indicates an almost ideal interconnection between the two subcells.

These devices are using an organic absorber for the narrow-gap subcell, which doesn’t need the high-temperature processing of silicon and is more stable than the commonly used narrow-bandgap perovskites based on Sn.

With the software Setfos from FLUXiM AG, they carried out optical simulations to identify the wide bandgap perovskite that matches the organic subcell.

Stefano Sem, Sandra Jenatsch, Kleitos Stavrou, Andrew Danos,

Andrew P. Monkman and Beat Ruhstaller

J. Mater. Chem. C, 2022, Advance Article

doi.org/10.1039/D1TC05594A

Thermally-activated delayed fluorescence (TADF) compounds are promising materials used in emissive layers of organic light-emitting diodes (OLEDs). Their main benefit is that they allow the internal quantum efficiency of the OLED to reach up to 100% by converting non-radiative triplet states into radiative singlets. Besides the importance of having a high reverse intersystem-crossing rate, which governs triplet conversion, minimizing the non-radiative decay processes is also extremely important to reach high efficiency. In this study the researchers provide a new method to quantify not only the most important decay rates involved in the TADF process, but also the non-radiative decay rates of both singlet and triplet states individually from transient and steady state experimental optical data.

Setfos was used to perform electro-optical simulations.

Wei Meng, Kaicheng Zhang, Andres Osvet, Jiyun Zhang, Wolfgang Gruber, Karen Forberich, Bernd Meyer, Wolfgang Heiss, Tobias Unruh, Ning Li, Christoph J. Brabec

Joule, Volume 6, Issue 2, 2022,

https://doi.org/10.1016/j.joule.2022.01.011

This research provides new insights into the identification of strain at the buried interfaces of perovskite thin films and reveals the strain-associated physical mechanisms impacting the performance and stability of perovskite solar cells.

Setfos was used to simulate the IV curve of perovskite cells with/without strain. They included the graded interface in the simulation and also the increased trap density.

Stephen Amoah, Xiangyu Fu, Shichen Yin, Qi Dong, Chen Dong, and Franky So

CS Appl. Mater. Interfaces 2022, 14, 7, 9377–9385

https://doi.org/10.1021/acsami.1c21128

The light outcoupling efficiency of a top-emitting organic light-emitting diode (OLED) is only about 20%, and the majority of the light is trapped in the waveguide modes and surface plasmon polariton (SPP) modes. Extracting the trapped modes can reduce the device power consumption and improve the operating lifetime. In this study, the researchers demonstrate a top-emitting OLED structure with a dielectric spacer to suppress the SPP mode and with a patterned back mirror to extract the waveguide modes.

Setfos to simulate the power dispersion of the reference device and overlayed it with the experimental ARES data

Mingyun Kang, Syed Zahid Hassan, Seong-Min Ko, Changwon Choi, Juhee Kim, Santosh K. R. Parumala, Yun-Hi Kim, Yun Hee Jang, Jinhwan Yoon, Dong-Woo Jee, Dae Sung Chung

Advanced Materials

doi.org/10.1002/adma.202200526

When the intensity of the incident light increases, the photocurrents of organic photodiodes (OPDs) exhibit relatively early saturation, due to which OPDs cannot easily detect objects against strong backlights, such as sunlight. In this study, this problem is addressed by introducing a light-intensity-dependent transition of the operation mode, such that the operation mode of the OPD autonomously changes to overcome early photocurrent saturation as the incident light intensity passes the threshold intensity. The photoactive layer is doped with a strategically designed and synthesized molecular switch, 1,2-bis-(2-methyl-5-(4-cyanobiphenyl)-3-thienyl)tetrafluorobenzene (DAB). The proposed OPD exhibits a typical OPD performance with an external quantum efficiency (EQE) of <100% and a photomultiplication behavior with an EQE of >100% under low-intensity and high-intensity light illuminations, respectively, thereby resulting in an extension of the photoresponse linearity to a light intensity of 434 mW cm?2. This unique and reversible transition of the operation mode can be explained by the unbalanced quantum yield of photocyclization/photocycloreversion of the molecular switch. The details of the operation mechanism are discussed in conjunction with various photophysical analyses. Furthermore, they establish a prototype image sensor with an array of molecular-switch-embedded OPD pixels to demonstrate their extremely high sensitivity against strong light illumination.

To further verify the effect of DAB_c on gain generation, the researchers conducted a numerical simulation using the Fluxim’s Setfos software to fit the experimentally obtained OPD data and determine the relevant fitting parameters.

Simon Zeder, Beat Ruhstaller, Urs Aeberhard

Phys. Rev. Applied 17, 014023 – Published 20 January 2022

https://doi.org/10.1103/PhysRevApplied.17.014023

Photon recycling (PR) is the re-absorption of internally emitted photons. Can it be another fundamental advantage of perovskites over other semiconductors in solar cells?

Simon Zeder and colleagues at FLUXiM AG discovered that PR could influence considerably the efficiency of MAPI-based solar cells. They coupled a wave optics approach with electronic transport simulations to treat photon recycling, rigorously. These simulations are showing that PR could increase the open-circuit voltage in pero-PVs by 50 mV in ideal conditions, and by 15 mV in the case of non-radiative recombination at the interfaces with MAPI. Further simulations show that the electron transporting layer (PCBM) and the back electrode (Ag) account for about 87% of the total parasitic absorption losses.

These results were obtained with the simulation software Setfos and can be used to design perovskite solar cells where photon recycling is an exploited beneficial effect.

Kevin Sutanto, Nurul Ridho Al Amin, Chih-Hsin Chen, Dian Luo, Chien-Hsin Chen, Sajal Biring, Chih-Chien Lee, Shun-Wei Liu

Organic Electronics, Volume 103, 2022, 106454, ISSN 1566-1199,

https://doi.org/10.1016/j.orgel.2022.106454.

Here the researchers report on a WO3/Al/Al:Ag anode which is demonstrated in a red OLED with superior performance compared to the ITO reference device. Better performance is due to narrower emission spectrum, improved outcoupling, lower turn-on voltage/better charge injection.

Setfos was used to simulate the forward emission spectrum and performed mode analysis for different ETL thicknesses.

Paios was also used to perform Impedance Spectroscopy at different voltages to check injection/accumulation of charges, performed C-V to analyse onset and show Transient Electroluminescence.

Ma, D., Lin, K., Dong, Y. et al.

Nature 599, 594–598 (2021).

doi.org/10.1038/s41586-021-03997-z

Light-emitting diodes (LEDs) based on perovskite quantum dots have shown external quantum efficiencies (EQEs) of over 23% and narrowband emission, but suffer from limited operating stability.

In this paper the researchers fabricate a more stable PeroLED by using fluorinated triphenylphosphine oxides to control the thickness distribution and passivate the surface of perovskite quantum wells (QWs) deposited in a film. The additive forms hydrogen bonds with the cations and gives energetically monodispersed QWs on a uniform film with high photoluminescence quantum yield. The fabricated pero-LEDs show green narrow emission with an EQE of 25.6% and an operating half-life of two hours at an initial luminance of 7,200 cd/m2.

The EQE is close to the theoretical outcoupling efficiency of these LEDs, as predicted by the simulation software Setfos. The optical simulations were performed using the Chance–Prock–Silbey model in Setfos.

Yi-Sheng Chen, Dian Luo, Wei-Chih Wei, Bo-Lin Chen, Tzu-Hung Yeh, Shun-Wei Liu, and Ken-Tsung Wong

Adv. Optical Mater. 2021, 2101952

DOI: 10.1002/adom.202101952

Prof. Wong and colleagues at the National Taiwan University tailored a special blend of organic molecules to reach a remarkable efficiency. This work is a perfect example of how to fine-tune the OLED emission via a combined simulation/experiment approach.

The team developed spirobifluorene-cored (SF) donors and blended them with CN-T2T acceptor for exciplex formation. This combination gives an electroluminescence peak at 584 nm. The emission increases to 760 nm with the further inclusion of the fluorescent emitter TTDSF. An optimized microcavity effect brings the emission to 774 nm.

The simulation software Setfos from allowed them to find the optimal thickness of the acceptor material (or ETL), and to optimize the optical cavity. The researchers measured an impressive EQE of 5.3% and stable performance of almost 300 hours for the optimized device.

Kai Oliver Brinkmann, Tim Becker, Florian Zimmermann, Cedric Kreusel, Tobias Gahlmann, Tobias Haeger, Thomas Riedl

Solar RRL (IF8.582), Pub Date : 2021-07-17,

doi/10.1002/solr.202100371

Optical simulations have been performed with the simulation software SETFOS that is based on a transfer matrix algorithm to calculate optical absorption, reflection, and transmission of a given assembly of layers. With the emergence of highly efficient perovskite solar cells in both single- and multijunction architectures, there is an abundance of reports of extremely high external quantum efficiencies (EQE) up to 98%.

These reports appear somewhat unrealistic and are sometimes subject to doubts or concerns of erroneous EQE measurements. In this report the researchers discuss and explain the root cause of the high EQE by a combination of experimental data and optical simulations.

Chin-Yiu Chan, Masaki Tanaka, Yi-Ting Lee, Yiu-Wing Wong, Hajime Nakanotani, Takuji Hatakeyama, and Chihaya Adachi

Nature Photonics, 15, 203–207, (2021)

https://www.nature.com/articles/s41566-020-00745-z

It is challenging to produce stable blue OLEDs with high efficiency and color purity. The researchers fabricated a new OLED showing pure-blue emission with high efficiency and stability. Their optimized device consists of a 2-unit stacked tandem OLED with a hyperfluorescent emitting layer. Setfos was used to fit angular photoluminescence data and determine the orientation of the dipoles of the TADF emitter.

Vasilopoulou, M., Mohd Yusoff, A.R.b., Daboczi, M. et al.

Nat Commun 12, 4868 (2021).

doi.org/10.1038/s41467-021-25135-z

In this paper, the team designed blue OLEDs with a new Hole Transport Material (HTM). By engineering the formation of exciplex excitons at the EML/ETL interface and subsequent FRET they managed to fabricate OLEDs with high efficiencies and turn-on voltage below band-gap. The device lifetime is longer than previously reported blue OLEDs, even if degradation due to the instability of the excited host molecule (typical in TADF OLEDs) is still an issue.

Setfos was used to help extract the dipole orientation of the TADF emitter from the analysis of angle-dependent PL spectra.

Felix Lang, Eike Köhnen, Jonathan Warby, Ke Xu, Max Grischek, Philipp Wagner, Dieter Neher, Lars Korte, Steve Albrecht, and Martin Stolterfoht

ACS Energy Letters 0, 6

DOI: 10.1021/acsenergylett.1c01783

In this paper the researchers present a thorough subcell diagnosis methodology to reveal deep insights into the practical efficiency limitations of state-of-the-art perovskite/silicon tandem PVs.

Setfos was used by the researchers to simulate band diagrams with either aligned energy levels or energy offsets in the perovskite subcell.

Jarla Thiesbrummel, Vincent M. Le Corre, Francisco Peña-Camargo, Lorena Perdigón-Toro, Felix Lang, Fengjiu Yang, Max Grischek, Emilio Gutierrez-Partida, Jonathan Warby, Michael D. Farrar, Suhas Mahesh, Pietro Caprioglio, Steve Albrecht, Dieter Neher, Henry J. Snaith, Martin Stolterfoht

Adv. Energy Mater. Sept. 2021, 2101447

doi.org/10.1002/aenm.202101447

In the paper, the researchers performed an analysis of current (performance) losses in PPV devices.

1) analyse changes in PLQY upon time (Voc -> Jsc) and link it to extraction problems caused by ions

2) perform various transient electric measurements to analyse electronic and ionic charge densities

They used the Absorption and Drift-Diffusion modules of Setfos to simulate transient current decay with mobile ions and 1) extract the ion density by fitting with experimental data, 2) show that electronic doping would not cause a current decay in contrast to ions and their experiments.

Hyeong Woo Bae, Yong Woo Kwon, Myungchan An, Junmo Kim, Jang Hyuk Kwon, and Donggu Lee

ACS Appl. Electron. Mater. 2021, 3, 7, 3240–3246

doi.org/10.1021/acsaelm.1c00406

In this paper, the researchers fabricated a tandem white OLED with a 20nm thin charge generation unit (CGU). Test subunits as well as first and second maxima (of the radiance plot) experimentally. Setfos was used to optimize layer thicknesses to get radiance peaks.

T. Ichikawa, A. Takagi, N. Yamada, K. Itonaga, H. Nakanotani, C. Adachi

Proceedings Volume 11788, Digital Optical Technologies; 117880P (2021)

doi.org/10.1117/12.2595135

In this paper, the researchers develop material and NIR-OLED stack which is finally integrated into a microdisplay. The application would be sensing. Setfos was used to optimize the cavity (tuning of HAT-CN layer).

Junmo Kim, Jeong Ha Hwang, Yong Woo Kwon, Hyeong Woo Bae, Myungchan An, Wonho Lee, Donggu Lee,

Organic Electronics, Volume 97, 2021, 106261,

doi.org/10.1016/j.orgel.2021.106261.

This report details the use of SiNx as encapsulation material. Thickness variation results on EQE were supported by I_OC simulations performed by Setfos.

Hyunsu Cho, Jinouk Song, Jin-Wook Shin, Jaehyun Moon, Byoung-Hwa Kwon, Jeong-Ik Lee, Seunghyup Yoo, and Nam Sung Cho

Optics Express (IF3.894), Pub Date : 2021-07-07

DOI: 10.1364/oe.430149

Description

In this paper, the researchers fabricated graphene-based electrodes for OLEDs. Multi-layer graphene electrodes were doped with TCNQ and their optical constants are measured.

Setfos was used to perform an angle-dependent emission simulation of the OLED with graphene electrodes to demonstrate the necessity and suitability of the nk data.

Dong Li, Jingwen Feng, Youqin Zhu, Zhigao Lu, Chen Pei, Zhuo Chen, Yanzhao Li, Xinguo Li & Xiaoguang X

Nano Res. (2021).

doi.org/10.1007/s12274-021-3596-4

In this paper, the researchers fabricated QLEDs with a top and bottom emission structure. They first electrically optimized the device (charge balance) and then optically improved the device in order to then change to a different ETL which optimizes both charge balance and optics at the same time. Setfos was used to perform an optical simulation of the QLEDs with different ETL thicknesses.

M. Lekshmi, S. Saroon, Ancy Albert, C.O. Sreekala

Materials Today Proceedings, Volume 46, Part 8, 2021, Pages 3114-3120

doi.org/10.1016/j.matpr.2021.02.682

Description:

In this work, a comparative study of inverted perovskite solar cells with different hole-transporting materials were fabricated out by simulation using the simulation software Setfos

J. I. Khan, S. Alsaggaf, R. S. Ashraf, B. Purushothaman, N. Chaturvedi, I. McCulloch, F. Laquai

Phys. Stat. Sol. (RRL) (2021)

https://doi.org/10.1002/pssr.202100206

The authors investigate charge carrier generation and recombination dynamics in blends of a novel wide-bandgap germanium-containing donor polymer, namely PEHGeNDT-BT, paired with either O-IDTBR or O-IDTBCN as a non-fullerene acceptor in BHJ solar cells by (ultrafast) transient spectroscopy and time-delayed collection field (TDCF) experiments. Carrier drift-diffusion simulations of the devices’ current-voltage (J-V) characteristics confirm that the experimentally determined kinetic parameters and process yields can reproduce the measured J-V curves under steady-state solar illumination.

E Knapp, M Battaglia, T Stadelmann, S Jenatsch, B Ruhstaller

8th Swiss Conference on Data Science, Lucerne, Switzerland, 9 June 2021

https://160.85.104.64/handle/11475/22414

In this paper, the authors combine the use of machine learning and a semiconductor device modelling tool (Setfos) to extract the material parameters from measurements and inturn train their machine learning model with synthetic training data originating from a semiconductor simulator. In a second step, the machine learning model is applied to a measured data set and determines the underlying material parameters. This novel and reliable method for the determination of material parameters paves the way to further device performance optimization.

Urs Aeberhard, Simon Zeder, Beat Ruhstaller

Optics Express, 29, (2021), 14773

PDF

Dr. Aeberhard and colleagues at FLUXiM AG presented a theoretical description of light emission, propagation, and re-absorption in semiconductor multilayer stacks is derived based on the transverse Green’s function of the electromagnetic field in the presence of a complex dielectric. The framework obtained is shown to reproduce the generalized Kirchhoff relations between the luminescent emission from metal halide perovskite slabs under uniform excitation and the slab absorptance of light with arbitrary angle of incidence.

Benjamin T. Feleki, Christ H. L. Weijtens, Martijn M. Wienk, and René A. J. Janssen

ACS Appl. Energy Mater. 2021, 4, 3033−3043

https://pubs.acs.org/doi/pdf/10.1021/acsaem.0c02653

The authors discovered that in a perovskite solar cell with an opaque substrate, parasitic optical absorption can be minimized by using a thin organic Hole Transport Layer, called NPB. The optical simulations of these solar cells were performed by using the transfer matrix method in Setfos. By exploiting simulations, designed an optimal stack before performing the actual experiments.

Yungui Li, Naresh B. Kotadiya, Bas van der Zee, Paul W. M. Blom, and Gert-Jan A. H. Wetzelaer

Adv. Optical Mater. 2021, 2001812,

https://onlinelibrary.wiley.com/doi/full/10.1002/adom.202001812

The authors developed a numerical model to simulate the fraction of photons coupled to air for OLEDs with a broad recombination zone. The dipole orientation of the CzDBA neat film was determined with Phelos by fitting the angular dependence of photoluminescence with Setfos software from Fluxim.

Tom P. A. van der Pol, René A. J. Janssen et al.

J. Phys. Chem. C March 4, 2021

https://doi.org/10.1021/acs.jpcc.0c11377

In this paper, the researchers analyze the performance of nonfullerene acceptors blends fabricated with solvent mixtures. The researchers used the Emission module of the simulation software Setfos to correct for self-absorption and interference effects of the PL and EL signals.

S. K. Kim, Dr. M. J. Park, Prof. J. H. Kwon

Adv. Photonics Res. 2021, 2000122

DOI: 10.1002/adpr.202000122

In this paper, the researchers optimize TEOLEDs with blue emitter, with a special focus on the top electrode. The researchers used the emission module of the simulation software Setfos to simulate different stacks and compare the results with the experiments.

Jaeho Lee, Jinouk Song, Jaehyeok Park, Seunghyup Yoo

Adv. Opt. Mat. 2021, 202002182

DOI: 10.1002/adom.202002182

In this paper, the researchers analyze the effect of low refractive index materials on outcoupling efficiency and different loss channels. The researchers used the emission module of the simulation software Setfos to produce benchmark optical simulations.

Chan, CY., Tanaka, M., Lee, YT. et al.

Nat. Photonics (2021).

https://doi.org/10.1038/s41566-020-00745-z

Organic light-emitting diodes (OLEDs) are a promising light-source technology for future generations of display. Despite great progress it is still challenging to produce blue OLEDs with sufficient colour purity, lifetime and efficiency for applications. This study presents a “3-component blue EML (new TADF assistant dopant; v-DABNA as (TADF)-narrow emitter; mCBP host) with pure color thanks to DABNA, but also higher EQE and LT95 thanks to the new emitter and the 3-component system. Use of the blue EML in a tandem configuration yielded an even higher EQE of 41%, lower CIEy coordinate (more blue) and better LT95 of >300 h (everything at 100 cd/m^2)." The Setfos Emission module was used for the emitter orientation fit. DABNA is more orientated than new emitter, yielding a higher EQE in the ternary EML.

Y. Liu, J. Wang, et al.

ACS Applied Nano Materials Article ASAP

DOI: 10.1021/acsanm.0c02797

A computer simulation study and parameter analysis are performed to demonstrate the fluorescent properties of the organic light-emitting diode (OLED) device structure. Setfos emission module was used in this simulation study.

Sharma, A., Das, T.D.

Opt Quant Electron 53, 83 (2021)

https://doi.org/10.1007/s11082-020-02707-9

In this paper, the researchers performed simulations and parameter analyses to demonstrate the fluorescent properties of the OLED device structure. Setfos emission module was used in this simulation study.

Hye In Yang, Jang Hyuk Kwon, et al.

Organic Electronics, Volume 89, 2021, 106031, ISSN 1566-1199,

https://doi.org/10.1016/j.orgel.2020.106031

This paper presents an efficient and stable green inverted organic light-emitting diode (IOLED) using multifunctional and strong nucleophilic quality electron transport material. Ag is used as n-type doping for ETMs (comparison to more popular Li). Ag doping results in similar performance but the stability is improved. The Setfos emission module was used to optimize the layer stack.

Dyson, M. J., van der, T. P. A., Meskers, S. C. J.

Adv. Optical Mater. 2021, 2001997.

https://doi.org/10.1002/adom.202001997

This study analyses the effect of cavity and self-absorption ("extrinsic") effects on measured PL spectra, focussing on 0-0/0-1 ratios. Setfos was used by the researchers to simulate absorption and emission of thin films.