publications-2011-to-2020

K. D. G. I. Jayawardena, R. M. I. Bandara, M. Monti,b E. Butler-Caddle,b T. Pichler, H. Shiozawa, Z. Wang, S. Jenatsch, S. J. Hinder, M. G. Masteghin, M. Patel, H. M. Thirimanne, W. Zhang, R. A. Sporea, J. Lloyd-Hughes and S. R. P. Silva

J. Mater. Chem. A 2020

https://doi.org/10.1039/C9TA10543C

The performance of all solar cells is dictated by charge recombination. A closer to ideal recombination dynamics results in improved performances, with fill factors approaching the limits based on Shockley–Queisser analysis. It is well known that for emerging solar materials such as perovskites, there are several challenges that need to be overcome to achieve high fill factors, particularly for large-area lead-tin mixed perovskite solar cells. Here we demonstrate a strategy towards achieving fill factors above 80% through post-treatment of a lead-tin mixed perovskite absorber with guanidinium bromide for devices with an active area of 0.43 cm2. This bromide post-treatment results in a more favorable band alignment at the anode and cathode interfaces, enabling better bipolar extraction. The resulting devices demonstrate an exceptional fill factor of 83%, approaching the Shockley–Queisser limit, resulting in a power conversion efficiency of 14.4% for large-area devices.

Daniele Braga, Sandra Jenatsch, Lieven Penninck, Roman Hiestand, Matthias Diethelm, Stéphane Altazin, Christoph Kirsch, Beat Ruhstaller

SID Symposium Digest of Technical Papers, 50: 953-956.

29 May 2019

doi.org/10.1002/sdtp.13083

We achieved a quantitative understanding of both electrical and optical coupling in OLED displays, by employing the simulation software LAOSS. For an AMOLED of around 300 PPI we found that the relative luminance between the addressed pixel and the neighbors can be as high as 40%, hampering significantly the quality of the final image. Similarly, in WOLEDs/CFs the light leakage to the neighboring pixels is clearly detectable, especially for wavelengths in the blue region of the spectrum.

Ru-Ze Liang, Maxime Babics, Akmaral Seitkhan, Kai Wang, Paul Bythell Geraghty, Sergei Lopatin, Federico Cruciani, Yuliar Firdaus, Marco Caporuscio, David J. Jones and Pierre M. Beaujuge

Advanced Functional Materials 28, 1705464 (2019)

DOI: 10.1002/adfm.201705464

Bei Yang, Yu Chen, Yong Cui, Delong Liu, Bowei Xu and Jianhui Hou

Adv. Energy Mater. 2018, 8, 1800698

https://doi.org/10.1002/aenm.201800698

Jung Hyuk Im, Kyung-Tae Kang, Jong Sun Choi and Kwan Hyun Cho

Journal of Luminescence 203, 540 (2018)

https://doi.org/10.1016/j.jlumin.2018.07.011

Jwo-Huei Jou, Jia-Wei Weng, Sudam Dhudaku Chavhan, Rohit Ashok Kumar Yadav, Tzu-Wei Liang

Journal of Physics D 51 (45), 454002 (2018)

https://doi.org/10.1088/1361-6463/aad951

Hyunsu Cho, Chul Woong Joo, Byoung-Hwa Kwon, Nam Sung Cho, Jonghee Lee

Organic Electronics 62, 72 (2018)

https://doi.org/10.1016/j.orgel.2018.07.016

Hyunkoo Lee, Jonghee Lee, Jeong-Ik Lee and Nam Sung Cho

Electronics 7,155 (2018)

https://doi.org/10.3390/electronics7090155

Dario Di Carlo Rasi, Koen H. Hendriks, Martijn M. Wienk, and René A. J. Janssen

Advanced Materials, 2018, 1803836

https://doi.org/10.1002/adma.201803836

Abstract:

A monolithic two-terminal solution-processed quadruple junction polymer solar cell in an n–i–p (inverted) configuration with four complementary polymer: fullerene active bulk-heterojunction layers is presented. The subcells possess different optical bandgaps ranging from 1.90 to 1.13 eV. Optical modeling using the transfer matrix formalism enables the prediction of the fraction of absorbed photons from sunlight in each subcell and determines the optimal combination of layer thicknesses. The quadruple junction cell features an open-circuit voltage of 2.45 V and has a power conversion efficiency of 7.6%, only slightly less than the modeled value of 8.2%. The external quantum efficiency spectrum, determined with appropriate light and voltage bias conditions, exhibits, in general, an excellent agreement with modeled spectrum. The device performance is presently limited by bimolecular recombination, which prevents using thick photoactive layers that could absorb light more efficiently.

Markus Regnat, Kurt P. Pernstich, Simon Züfle, and Beat Ruhstaller

ACS Applied Materials & Interfaces 10,31552 (2018)

https://doi.org/10.1021/acsami.8b09595

Abstract: From s-polarized, angle-dependent measurements of the electroluminescence spectra in a three-layer phosphorescent organic light-emitting diode, we calculate the exciton distribution inside the 35 nm thick emission layer. The shape of the exciton profile changes with the applied bias due to differing field dependencies of the electron and hole mobilities. A split emission zone with high exciton densities at both sides of the emission layer is obtained, which is explained by the presence of energy barriers and similar electron and hole mobilities. A peak in the transient electroluminescence signal after turn-off and the application of a reverse bias is identified as a signature of a split emission zone.

S. Jenatsch, S. Altazin, P.-A. Will, M. T. Neukom, E. Knapp, S. Züfle, S. Lenk, S. Reineke, and B. Ruhstaller

Journal of Applied Physics 124, 105501 (2018)

https://doi.org/10.1063/1.5044494

Abstract: Single-carrier devices are an excellent model system to study charge injection and charge transport properties of (doped) transport layers and to draw conclusions about organic electronics devices in which they are used. By combining steady-state and impedance measurements at varying temperatures of hole-only devices with different intrinsic layer thicknesses, we are able to determine all relevant material parameters, such as the charge mobility and the injection barrier. Furthermore, the correlation and sensitivity analyses reveal that the proposed approach to study these devices is especially well suited to extract the effective doping density, a parameter that cannot be easily determined otherwise. The effective doping density is crucial in organic light-emitting diodes (OLEDs) for realizing efficient injection, charge balance, and lateral conductivity in display or lighting applications. With the fitted drift-diffusion device model, we are further able to explain the extraordinary two-plateau capacitance–frequency curve of these hole-only devices, which originates from charges that flow into the intrinsic layer at zero applied offset voltage. We demonstrate that the observation of this behavior is a direct indication for ideal charge injection properties and the observed capacitance–frequency feature is linked to the charge carrier mobility in the intrinsic layer. The extracted material parameters may directly be used to simulate and optimize full OLED devices employing the investigated hole-injection and -transport materials.

Stéphane Altazin, Lieven Penninck, and Beat Ruhstaller

Handbook of Organic Light-Emitting Diodes, Springer Nature 2018

https://doi.org/10.1007/978-4-431-55761-6_21-1

Jin Xu, Andreas Sandström, Erik Mattias Lindh, Wei Yang, Shi Tang, and Ludvig Edman

ACS Appl. Mater. Interf., 2018. 10 , 33380

https://doi.org/10.1021/acsami.8b13036

Akanksha Jetly and Rajesh Mehra

International Journal of Optics

Volume 2018, Article ID 9458530

https://doi.org/10.1155/2018/9458530

Kyungnam Kang, Kyoung-Youm Kim, and Jungho Kim

Optics Express 26, A955 (2018)

https://doi.org/10.1364/OE.26.00A955

Sheng Bi, Zhongliang Ouyang, Shoieb Shaik and Dawen Li

Scientific Reports 8, 9574 (2018)

https://doi.org/10.1038/s41598-018-27868-2

S. Altazin, C. Kirsch, E. Knapp, A. Stous, and B. Ruhstaller

Journal of Applied Physics 124, 135501 (2018)

https://doi.org/10.1063/1.5043245

Abstract: We present a new approach to simulate the transport of charges across organic/organic layer interfaces in organic semiconductor devices. This approach combines the drift-diffusion formalism away from the interface with a hopping description of the charge transport in the vicinity of the interface. It has been implemented in the commercial software SETFOS allowing for fast simulations of the complete device. This new model takes into account both recombination and generation mechanisms across the interface enabling the modeling of charge-generation/recombination interfaces for the numerical simulation of tandem devices. Using this approach, it is also possible to simulate devices using 1,4,5,8,9,11-Hexaazatriphenylenehexacarbonitrile as a hole-injection layer. This particular material has a very deep HOMO level (approximately 9.5 eV), which would seemingly prevent such a layer to be used as a hole-injection material in the framework of traditional drift-diffusion models.

Michele De Bastiani, Erkan Aydin, Thomas Allen, Daniel Walter, Andreas Fell, Jun Peng, Nicola Gasparini, Joel Troughton, Derya Baran, Klaus Weber, Thomas P. White, and Stefaan De Wolf

Advanced Electronic Materials 2018, 1800500

https://doi.org/10.1002/aelm.201800500

Abstract: Charge accumulation at the electron and hole transport layers generates anomalous electrical behavior in perovskite solar cells (PSCs). Hysteresis in the current voltage characteristic and recombination at the interfaces are the clearest manifestations of this phenomenon, which compromises device performance and stability. Here, the underlying charge-carrier dynamics of a variety of PSCs are investigated by analyzing their transient photocurrent response. Towards shorter time scales, PSCs often show increasingly severe hysteretic responses. This phenomenon is correlated with the presence of interfacial accumulated charges that hinders the photogenerated carrier extraction process. However, introducing passivating contacts improves the carrier-injection properties and the devices become completely hysteresis free. These results underline the importance of contact passivation for PSCs and the need to further develop new passivating interlayers that simultaneously eliminate charge-carrier recombination and provide selective transport for each carrier type at the PSC’s contacts.

Yuan Xiong, Long Ye, Abay Gadisa, Qianqian Zhang, Jeromy James Rech, Wei You, and Harald Ade

Advanced Functional Materials 2018, 1806262

https://doi.org/10.1002/adfm.201806262

Taesoo Kim, Yuliar Firdaus, Ahmad R. Kirmani, Ru-Ze Liang, Hanlin Hu, Mengxia Liu, Abdulrahman El Labban, Sjoerd Hoogland, Pierre M. Beaujuge, Edward H. Sargent, and Aram Amassian

ACS Energy Letters 3, 1307 (2018)

https://doi.org/10.1021/acsenergylett.8b00460

Indunil Angunawela, Long Ye, Haijun Bin, Zhi-Guo Zhang, Abay Gadisa, Yongfang Li and Harald Ade

Materials Chemistry Frontiers, 2018

https://doi.org/10.1039/C8QM00503F

Jwo-Huei Jou, Tzu-Chieh Tai, Yu-Ting Su, Hui-Huan Yu, Chi-Heng Chiang, Sudam D. Chavhan, You-Ting Lin, Jing-Jong Shyue, and Tzu-Wei Liang

Physica status solidi A, 2018

https://doi.org/10.1002/pssa.201800390

Akanksha Jetly, Rajesh Mehra

Optical Materials 88, 304 (2019)

https://doi.org/10.1016/j.optmat.2018.11.051

Francisco Peña-Camargo, Jarla Thiesbrummel, Hannes Hempel, Artem Musiienko, Vincent M. Le Corre, Jonas Diekmann, Jonathan Warby, Thomas Unold, Felix Lang, Dieter Neher, Martin Stolterfoht;

Applied Physics Reviews 1 June 2022; 9 (2): 021409. 86

https://doi.org/10.1063/5.00852

This scientific article presents a multifaceted approach to determine the electronic doping density in metal-halide perovskite systems. The researchers used various optical and electrical characterization techniques to quantify the doping density. The results showed that the doping density in perovskite thin films is below the critical threshold that would affect device performance. The doping-induced charges were found to be too low to redistribute the built-in voltage in the perovskite active layer. However, the presence of mobile ions in sufficient quantities was observed, which could create space-charge regions in the active layer. The experimental results were supported by drift-diffusion simulations. The findings suggest that perovskite thin films behave as intrinsic semiconductors and that doping does not significantly influence the performance of devices based on these materials.

How was Setfos used

Setfos was used to check that findings for doping also holds for mobile ions.

Markus Regnat, Kurt P. Pernstich, Beat Ruhstaller

Organic Electronics 70, 219-226 (2019)

https://doi.org/10.1016/j.orgel.2019.04.027

Abstract:
We present an electro-optical model of a three-layer phosphorescent OLED which accurately describes the measured current efficiency and transient electroluminescence decay for different biases. Central findings are a bias-dependent emission zone, which influences light outcoupling as well as exciton quenching, and the presence of strong triplet-polaron quenching even at low bias. The measured current efficiency initially increases up to 9 V before it decreases, where the increase is found to be caused by reduced triplet-polaron quenching with holes, while the decrease is caused by a reduced light outcoupling and increased triplet-triplet annihilation. The numerical model allows identifying the individual contributions of the exciton continuity equation and explains the electroluminescence decay, which deviates significantly from a mono-exponential decay due to the dominating influence of exciton generation and quenching after the external bias is removed.

Luiz Gustavo Simão Albano, João Vitor Paulin, Luciana Daniele Trino, Silvia Leticia Fernandes, Carlos Frederico de Oliveira Graeff

Journal of Applied Polymer Science 136, 47805 (2019)

https://dx.doi.org/10.1002/APP.47805

Paramaguru Ganesan, Wen-Yi Hung, Jen-Yung Tso, Chang-Lun Ko, Tsai-Hui Wang, Po-Ting Chen, Hsiu-Fu Hsu, Shih-Hung Liu, Gene-Hsiang Lee, Pi-Tai Chou, Alex K.-Y. Jen and Yun Chi

Advanced Functional Materials 2019, 1900923

https://doi.org/10.1002/adfm.201900923

Jafar I. Khan, Raja S. Ashraf, Maha A. Alamoudi, Mohammed N. Nabi, Hamza N. Mohammed, Andrew Wadsworth, Yuliar Firdaus, Weimin Zhang, Thomas D. Anthopoulos, Iain McCulloch, Frédéric Laquai

Solar RRL (2019)

https://doi.org/10.1002/solr.201900023

Kyungnam Kang and Jungho Kim

Journal of the Korean Physical Society 74, 649 (2019)

https://dx.doi.org/10.3938/jkps.74.649

Rita Rana and Rajesh Mehra

Journal of Electronic Materials (2019)

https://doi.org/10.1007/s11664-019-07221-7

Youqin Zhu, Abay Gadisa, Zhengxing Peng, Masoud Ghasemi, Long Ye, Zheng Xu, Suling Zhao, and Harald Ade

Advanced Energy Materials 1900376 (2019)

https://doi.org/10.1002/aenm.201900376

Yuliar Firdaus, Vincent M. Le Corre, Jafar I. Khan, Zhipeng Kan, Frédéric Laquai, Pierre M. Beaujuge, and Thomas D. Anthopoulos

Advanced Science 1802028 (2019)

https://doi.org/10.1002/advs.201802028

Jin-Wook Shin

Dissertation, Tohoku University 2019

http://hdl.handle.net/10097/00125213

Robin E. M. Willems, Stefan C.J. Meskers, Martijn M. Wienk, and René A. J. Janssen

J. Phys. Chem. C (2019)

https://dx.doi.org/10.1021/acs.jpcc.9b00568

Ik Jang Ko, Hyuna Lee, Jin Hwan Park, Gyeong Woo Kim, Raju Lampande, Ramchandra Pode and Jang Hyuk Kwon

Phys. Chem. Chem. Phys. 21, 7083 (2019)

https://doi.org/10.1039/c9cp00965e

Jingyang Xiao, Minrun Ren, Guichuan Zhang, Jianbin Wang, Donglian Zhang, Linlin Liu, Ning Li, Christoph J. Brabec, Hin-Lap Yip and Yong Cao

Solar RRL 201900077 (2019)

https://doi.org/10.1002/solr.201900077

Alfian F. Madsuha, Chuyen Van Pham, Michael Eck, Martin Neukom, and Michael Krueger

Journal of Nanomaterials, Article ID 6095863 (2019)

https://doi.org/10.1155/2019/6095863

Zhenchao Li, Ziming Chen, Yongchao Yang, Qifan Xue, Hin-Lap Yip and Yong Cao

Nature Communications 10:1027 (2019)

https://doi.org/10.1038/s41467-019-09011-5

Abstract:

In recent years, substantial progress has been made in developing perovskite light-emitting diodes with near-infrared, red and green emissions and over 20% external quantum efficiency. However, the development of perovskite light-emitting diodes with blue emission remains a great challenge, which retards further development of full-color displays and white-light illumination based on perovskite emissive materials. Here, firstly, through composition and dimensional engineering, we prepare quasi-two-dimensional perovskite thin films with improved blue emission, taking advantages of reduced trap density and enhanced photoluminescence quantum yield. Secondly, we find a vertically non-uniform distribution of perovskite crystals in the PEDOT:PSS/perovskite hybrid film. Through modulating the position of the recombination zone, we activate the majority of quasi-two-dimensional perovskite crystals, and thus demonstrate the most efficient blue perovskite light-emitting diode to date with emission peak at 480 nm, record luminance of 3780 cd m−2 and record external quantum efficiency of 5.7%.

Simon Züfle, Rickard Hansson, Eugene A. Katz, Ellen Moons

Solar Energy 183 (2019) 234–239

https://doi.org/10.1016/j.solener.2019.03.020

https://authors.elsevier.com/c/1YiXX,tRdATFb

Abstract:

Encapsulated organic solar cells often show a burn-in behaviour under illumination. This burn-in manifests itself as a rapid performance loss followed by a much slower progression of the degradation. Here we investigate the burn-in for PCDTBT:PC70BM solar cells under a wide range of illumination intensities. We find that increasing the sunlight concentration from 1 Sun to up to 100 Suns does not change the degradation behaviour, i.e. the dependence of all principal photovoltaic parameters on the dose of solar exposure (in Sun hours). This suggests that the degradation mechanisms under solar concentration (≤100 Suns) are the same as those observed under 1 Sun. This result makes it possible to use concentrated sunlight for accelerated stability assessment of these devices. We also find that devices with PEDOT:PSS as hole transport material show a rapid drop in open-circuit voltage of around 100 mV during the first Sun hour of light exposure. By replacing PEDOT:PSS with MoO3 this initial process can be prevented and only the much slower part of the photo-degradation takes place.

Jelena Vujančević, Pavao Andričević, Anđelika Bjelajac, Veljko Đokić, Maja Popović, Zlatko Rakočević, Endre Horváth, Márton Kollár, Bálint Náfrádi, Andreas Schiller, Kondrad Domanski, László Forró, Vera Pavlović, Đorđe Janaćković

Ceramics International 45,10013 (2019)

https://doi.org/10.1016/j.ceramint.2019.02.045

Abstract:
Highly ordered, anodically grown TiO2 nanotubes on titanium supports were annealed in ammonia atmosphere in order to incorporate nitrogen doping (. 2 at.%) in the titanium oxide lattice. FESEM micrographs revealed nanotubes with an average outer diameter of 101.5 ± 1.5 nm and an average wall thickness of about 13 nm. Anatase crystals were formed inside the tubes after annealing in ammonia atmosphere for 30 min. With further annealing, rutile peaks appeared due to the thermal oxidation of the foil and rise as the duration of heat treatment was increased. The concentration and chemical nature of nitrogen in the nanotube arrays can be correlated to the optical response of dry-pressed heterojunctions of doped TiO2/CH3NH3PbI3 single crystals. The N-TiO2/perovskite heterojunction with the highest amount of interstitial nitrogen exhibited an improved photocurrent, indicating the importance of the semiconductor doping-based heterojunction optimization strategies to deliver competitive levels of halide perovskite-based optoelectronic devices to be envisioned for urban infrastructures.

Dario Di Carlo Rasi, Pieter M. J. G. van Thiel, Haijun Bin, Koen H. Hendriks, Gaël H. L. Heintges, Martijn M. Wienk, Tim Becker, Yongfang Li, Thomas Riedl, and Ren
e A. J. Janssen

Solar RRL 2019, 1800366

https://doi.org/10.1002/solr.201800366

Wolfgang Tress, Konrad Domanski, Brian Carlsen, Anand Agarwalla, Essa A. Alharbi, Michael Graetzel and Anders Hagfeldt

Nature Energy 4, 568 (2019)

https://www.nature.com/articles/s41560-019-0400-8

Description:

W. Tress and co-authors characterized and analyzed the performance of an efficient perovskite solar cell (PSC) under simulated ambient conditions based on real temperature and irradiance data from selected days over one year at a location in central Europe. They find that the PSC shows only a low decrease of efficiency with elevated temperature and low light intensity, maintaining almost optimum values for ambient conditions, under which most of the solar energy is incident on the solar cell.

Meiyue Liu, Ziming Chen, Zhen Chen, Hin-lap Yip and Yong Cao

Mater. Chem. Front., 2019

https://doi.org/10.1039/C8QM00620B

Abstract:
The tandem architecture for perovskite solar cells has proven successful in promoting the development of such cells. A low-bandgap perovskite solar cell, which typically acts as a back cell, is one of the critical components for tandem perovskite solar cells. However, nowadays, highly efficient low-bandgap perovskite solar cells are mostly based on the inverted structure, which restricts the development of conventional perovskite tandem cells. Therefore, efficient low-bandgap perovskite solar cells based on the conventional structure need to be developed to further extend the availability of device architectures and interfacial materials for tandem cells. Here, by modifying the electron transport materials, we successfully demonstrated an efficient low-bandgap perovskite solar cell based on conventional structure. A ZnO/SnO2/C60-SAM tri-layer was used to engineer the energy level alignment of electron transport layers to reduce the energy loss occurring at the interface and simultaneously suppress the interfacial recombination and improve the charge extraction, resulting in a reduced open-circuit voltage loss for the device. Finally, our low-bandgap perovskite solar cells achieved a power conversion efficiency of 13.8%, which is the record result for conventional device structures to date.

Masaki Tanaka, Hiroki Noda, Hajime Nakanotani, and Chihaya Adachi

Adv. Electron. Mater. 2019, 1800708

https://doi.org/10.1002/aelm.201800708

Abstract:

The relatively short device lifetime of blue organic light‐emitting diodes (OLEDs) when compared with the lifetimes of green and red OLEDs is one of the crucial problems that must be overcome to enable practical application of these devices to full‐color OLED displays. This work focuses on the degradation phenomena of OLEDs that are based on sky‐blue thermally activated delayed fluorescence emitters and clarifies the degradation mechanisms based on spectral change of the electroluminescence, which indicates the formation of electromer emission from an electron transport layer. Additionally, it is determined that the change in the carrier balance that occurs during this degradation process can be ascribed to the formation of electron traps.

Jwo-Huei Jou, You-Ting Lin, Yu-Ting Su, Wei-Chi Song, Shiv Kumar, Deepak Kumar Dubey, Jing-Jong Shyue, Hsun-Yun Chang, Yun-Wen You, Tzu-Wei Liang

Organic Electronics 67 (2019) 222

https://doi.org/10.1016/j.orgel.2019.01.035

Chenyi Yang, Ningning Liang, Long Ye, Harald Ade, Xiaotao Yuan, Jianhui Hou

Organic Electronics 68 (2019) 15

https://doi.org/10.1016/j.orgel.2019.01.047

Francesco Pagani, Evelyn Stilp, Reto Pfenninger, Eduardo Cuervo Reyes, Arndt Remhof, Zoltan Balogh-Michels, Antonia Neels, Jordi Sastre-Pellicer, Michael Stiefel, Max Döbeli, Marta D Rossell, Rolf Erni, Jennifer L.M. Rupp, and Corsin Battaglia

ACS Appl. Mater. Interfaces, 2018

https://doi.org/10.1021/acsami.8b16519

Abstract:

Using an epitaxial thin-film model system deposited by pulsed laser deposition (PLD), we study the Li-ion conductivity in Li4Ti5O12, a common anode material for Li-ion batteries. Epitaxy, phase purity, and film composition across the film thickness are verified employing out-of-plane and in-plane X-ray diffraction, transmission electron microscopy, time-of-flight mass spectrometry, and elastic recoil detection analysis. We find that epitaxial Li4Ti5O12 behaves like an ideal ionic conductor that is well described by a parallel RC equivalent circuit, with an ionic conductivity of 2.5 × 10–5 S/cm at 230 °C and activation energy of 0.79 eV in the measured temperature range of 205 to 350 °C. Differently, in a co-deposited polycrystalline Li4Ti5O12 thin film with an average in-plane grain size of <10 nm, a more complex behavior with contributions from two distinct processes is observed. Ultimately, epitaxial Li4Ti5O12 thin films can be grown by PLD and reveal suitable transport properties for further implementation as zero-strain and grain boundary-free anodes in future solid-state microbattery designs.

Yingying Zhang, Xiong Li, Denghui Xu, Fanwen Meng, Rong Hu, Jia Zhao

Surface & Coatings Technology, 2018

https://doi.org/10.1016/j.surfcoat.2018.11.074

Yi-Ting Lee, Po-Chen Tseng, Takeshi Komino, Masashi Mamada, Ruby Janet Ortiz, Man-Kit Leung, Tien-Lung Chiu, Chi-Feng Lin, Jiun-Haw Lee, Chihaya Adachi, Chao-Tsen Chen, and Chin-Ti Chen

ACS Appl. Mater. Interfaces, 2018

https://doi.org/10.1021/acsami.8b16199

Ru-Ze Liang, Maxime Babics, Victoria Savikhin, Weimin Zhang, Vincent M. Le Corre, Sergei Lopatin, Zhipeng Kan, Yuliar Firdaus, Shengjian Liu, Iain McCulloch, Michael F. Toney, and Pierre M. Beaujuge

Adv. Energy Mater. 2018, 8, 1800264

https://doi.org/10.1002/aenm.201800264

Matthias Diethelm, Quirin Grossmann, Andreas Schiller, Evelyne Knapp, Sandra Jenatsch, Maciej Kawecki, Frank Nüesch, and Roland Hany

Adv. Optical Mater. 2018, 1801278

https://doi.org/10.1002/adom.201801278

Abstract: Effects of ion concentration and active layer thickness play a critical role in the performance of light-emitting electrochemical cells. Expanding on a pioneering materials system comprising the super yellow (SY) polymer and the electrolyte trimethylolpropane ethoxylate (TMPE)/Li+CF3SO3 -, it is reported that a slightly lowered salt concentration and layer thickness result in a substantial efficiency increase and that this increase is confined to a narrow concentration and thickness range. For a film thickness of 70 nm, a blend ratio SY:TMPE:Li+CF3SO3 - = 1:0.075:0.0225, and a current of 7.7 mA cm-2 the current efficacy is 11.6 cd A-1, on a par with SY light-emitting diodes. The optimized salt content can be explained by increased exciton quenching at higher concentrations and hindered carrier injection and conduction at lower concentrations, while the optical dependence on the layer thickness is due to weak microcavity effects. A comprehensive optical modeling study is presented, which includes the doping-induced changes of the refractive indices and self-absorption losses due to the emission–absorption overlap of intrinsic and doped SY. The analysis indicates either a thickness-independent emitter position (EP) close to the anode or a thickness-dependent EP, shifted to the cathode for increased thicknesses.

Paramaguru Ganesan, Deng-Gao Chen, Jia-Ling Liao, Wei-Cheng Li, Yi-Ning Lai, Dian Luo, Chih-Hao Chang, Chang-Lun Ko, Wen-Yi Hung, Shun-Wei Liu, Gene-Hsiang Lee, Pi-Tai Chou and Yun Chi

J. Mater Chem. C, 2018, 6, 10088-10100

Toshinori Matsushima, Chuanjiang Qin, Kenichi Goushi, Fatima Bencheikh, Takeshi Komino, Matthew Leyden, Atula S. D. Sandanayaka, and Chihaya Adachi

Adv. Mater. 2018, 1802662

https://doi.org/10.1002/adma.201802662

Abstract: The development of host materials with high performance is essential for the fabrication of efficient and stable organic light-emitting diodes (OLEDs). Although host materials used in OLEDs are typically organics, in this study, it is shown that the organic-inorganic perovskite CH3NH3PbCl3 (MAPbCl3) can be used as a host layer for OLEDs. Vacuum-evaporated MAPbCl3 films have a wide bandgap of about 3 eV and very high and relatively balanced hole and electron mobilities, which are suitable for the host material. Photoluminescence and electroluminescence take place through energy transfer from MAPbCl3 to an organic emitter in films. The incorporation of a MAPbCl3 host layer into OLEDs leads to a reduction of driving voltage and enhancement of external quantum efficiency as compared to devices with a conventional organic host layer. Additionally, OLEDs with a MAPbCl3 host layer demonstrate very good operational stability under continuous current operation. These results can be extensively applied to organic- and perovskite-based optoelectronics.

Lieven Penninck, Matthias Diethelm, Stéphane Altazin, Roman Hiestand, Christoph Kirsch, Beat Ruhstaller

Journal of the SID 26, 546 (2018)

https://doi.org/10.1002/jsid.671

Shu-Wei Li, Cheng-Hung Yu, Chang-Lun Ko, Tanmay Chatterjee, Wen-Yi Hung and Ken-Tsung Wong

ACS Appl. Mater. Interfaces 2018, 10, 12930−12936

https://doi.org/10.1021/acsami.8b02766

Shuai-Shuai Meng, Yan-Qing Li and Jian-Xin Tang

Organic Electronics 61, 351 (2018)

https://doi.org/10.1016/j.orgel.2018.06.014

Laura Ciammaruchi et al.

Journal of Materials Research 33 (13), pp. 1909-1924 (2018)

https://doi.org/10.1557/jmr.2018.163

Elisabeth Bodenstein, Matthias Schober, Marie Hoffmann, Christoph Metzner, Uwe Vogel

Journal of the SID, 2018 , 26, 555

https://doi.org/10.1002/jsid.674

Alejandro N. Filippin, Tzu-Ying Lin, Michael Rawlence, Tanja Zünd, Kostiantyn Kravchyk, Jordi Sastre-Pellicer, Stefan G. Haass, Aneliia Wäckerlin, Maksym V. Kovalenkoab and Stephan Buecheler

RSC Adv., 2018, 8, 20304

https://doi.org/10.1039/C8RA02461H

Abstract:

To obtain full advantage of state-of-the-art solid-state lithium-based batteries, produced by sequential deposition of high voltage cathodes and promising oxide-based electrolytes, the current collector must withstand high temperatures (>600 °C) in oxygen atmosphere. This imposes severe restrictions on the choice of materials for the first layer, usually the cathode current collector. It not only must be electrochemically stable at high voltage but also remain conductive upon deposition and annealing of the subsequent layers without presenting a strong diffusion of its constituent elements into the cathode. A novel cathode current collector based on a Ni-Al–Cr superalloy with target composition Ni0.72Al0.18Cr0.10 is presented here. The suitability of this superalloy as a high voltage current collector was verified by determining its electrochemical stability at high voltage by crystallizing and cycling LiCoO2 directly onto it.

Martin Neukom, Simon Züfle, Sandra Jenatsch, Beat Ruhstaller

Science Tech. Adv. Mater., 2018, 19, 291

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https://doi.org/10.1080/14686996.2018.1442091

Abstract: We present an overview of opto-electronic characterization techniques for solar cells including light-induced charge extraction by linearly increasing voltage, impedance spectroscopy, transient photovoltage, charge extraction and more. Guidelines for the interpretation of experimental results are derived based on charge drift-diffusion simulations of solar cells with common performance limitations. It is investigated how nonidealities like charge injection barriers, traps, and low mobilities among others manifest themselves in each of the studied cell characterization techniques. Moreover, comprehensive parameter extraction for an organic bulk-heterojunction solar cell comprising PCDTBT:PC70BM is demonstrated. The simulations reproduce the measured results of 9 different experimental techniques. Parameter correlation is minimized due to the combination of various techniques. Thereby a route to comprehensive and accurate parameter extraction is identified.

Tzu-Hung Yeh, Chih-Chien Lee, Chun-Jen Shih, Gautham Kumar, Sajal Biring, Shun-Wei Liu

Organic Electronics 59, 266 (2018)

https://doi.org/10.1016/j.orgel.2018.05.014

S. Altazin, L. Stepanova, J. Werner, B. Niesen, C. Ballif, and B. Ruhstaller

Optics Express 26, A579 (2018)

https://doi.org/10.1364/OE.26.00A579

Abstract:We present an optical model implemented in the commercial software SETFOS 4.6 for simulating perovskite/silicon monolithic tandem solar cells that exploit light scattering structures. In a first step we validate the model with experimental data of tandem solar cells that either use front- or rear-side textures and extract the internal quantum efficiency of the methyl-ammonium lead iodide (MALI) perovskite sub-cell. In a next step, the software is used to investigate the potential of different device architectures featuring a monolithic integration between the perovskite and silicon sub-cells and exploiting rear- as well as front-side textures for improved light harvesting. We find that, considering the available contact materials, the p-i-n solar cell architecture is the most promising with respect to achievable photocurrent for both flat and textured wafers. Finally, cesium-formamidinium-based perovskite materials with several bandgaps were synthetized, optically characterized and their potential in a tandem device was quantified by simulations. For the simulated layer stack and among the tested materials with bandgaps of 1.7 and 1.6 eV, the one with 1.6 eV bandgap was found to be the most promising, with a potential of reaching a power conversion efficiency of 31%. In order to achieve higher efficiencies using higher band-gap materials, parasitic absorptance in the blue spectral range should be further reduced.

Dario Di Carlo Rasi, Koen H. Hendriks, Gaël H. L. Heintges, Giulio Simone, Gerwin H. Gelinck, Veronique S. Gevaerts, Ronn Andriessen, Geert Pirotte,Wouter Maes, Weiwei Li, Martijn M. Wienk, and René A. J. Janssen

Sol. RRL, 2018, 2, 1800018

https://onlinelibrary.wiley.com/doi/pdf/10.1002/solr.201800018

Andrius Devižis, Sandra Jenatsch, Matthias Diethelm, Vidmantas Gulbinas, Frank Nüesch, Roland Hany

ACS Photonics, 2018, 5 (8), pp 3124-3131

https://pubs.acs.org/doi/10.1021/acsphotonics.8b00358

Karen Strassel, Adrian Kaiser, Sandra Jenatsch, Anna C. Véron, Surendra B. Anantharaman, Erwin Hack, Matthias Diethelm, Frank Nüesch, Rian Aderne, Cristiano Legnani, Sergii Yakunin, Marco Cremona, and Roland Hany

ACS Appl. Mater. Interf., 2018, 10, 11063

https://pubs.acs.org/doi/10.1021/acsami.8b00047

Amin Salehi, Ying Chen, Xiangyu Fu, Cheng Peng, and Franky So

ACS Appl. Mater. Interf., 2018, 10, 9595

https://pubs.acs.org/doi/10.1021/acsami.7b18514

So-Ra Park and Min Chul Suh

Optics Express, 2018, 26, 4979

https://doi.org/10.1364/OE.26.004979

Lei Wang, Sandra Jenatsch, Beat Ruhstaller, Christian Hinderling, Donatas Gesevicius, Roland Hany, and Frank Nüesch

Advanced Functional Materials 28,1705724 (2018)

https://doi.org/10.1002/adfm.201705724

Matthias Diethelm, Lieven Penninck, Stéphane Altazin, Roman Hiestand, Christoph Kirsch & Beat Ruhstaller

Journal of Information Display, 2018, 19, 61

https://doi.org/10.1080/15980316.2018.1428232

Abstract:The resolution of organic light-emitting diode (OLED) displays is increasing steadily as these displays are adopted for mobile and virtual reality (VR) devices. This leads to a stronger pixel crosstalk effect, where the neighbors of active pixels unintentionally emit light due to a lateral electric current between the pixels. Recently, the crosstalk was quantified by measuring the current flowing through the common hole transport layer between the neighboring pixels and comparing it to the current through the active pixel diode [S.-K. Kwon, K.-S. Kim, H.-C. Choi and J. H. Kwon, presented at the International Meeting on Information Display, Jeju, South Korea, 2016]. The measurements showed that the crosstalk is more crucial for low light levels. In such cases, the intended and parasitic currents are similar. The simulations performed in this study validated these measurement results. By simulations, we quantify the crosstalk current through the diode. The luminous intensity can be calculated with the measured current efficiency of the diodes. For low light levels, the unintended luminance can reach up to 40% of the intended luminance. The luminance due to pixel crosstalk is perceivable by humans. This effect should be considered for OLED displays with resolutions higher than 300 PPI.

Dae-Hyeon Kim, Anthony D’Aléo, Xian-Kai Chen, Atula D. S. Sandanayaka, Dandan Yao, Li Zhao, Takeshi Komino, Elena Zaborova, Gabriel Canard, Youichi Tsuchiya, Eunyoung Choi, Jeong Weon Wu, Frédéric Fages, Jean-Luc Brédas, Jean-Charles Ribierre and Chihaya Adachi

Nature Photonics, Vol. 12, February 2018. p. 98–104

https://doi.org/10.1038/s41566-017-0087-y

Sandra Jenatsch, Markus Regnat, Roland Hany, Matthias Diethelm, Frank Alain Nüesch, and Beat Ruhstaller

ACS Photonics 5, 1591 (2018)

https://pubs.acs.org/doi/abs/10.1021/acsphotonics.8b00047

Abstract:Light-emitting electrochemical cells (LECs) are one of the simplest electroluminescent devices and consist of a single emissive organic/salt layer sandwiched between two electrodes. The unique attribute of an operated LEC is the development of a pdoped/ intrinsic/n-doped (p-i-n) structure in the active layer in which the doped regions allow for facile transport of electronic charges to the intrinsic region, where charge recombination and light emission occur. However, due to the complex and simultaneous motion of ionic and electronic charges, the examination of the p-i- n structure and the zone where the light is emitted (EZ) is challenging during operation. By analyzing incident photon-tocurrent conversion efficiency and angular emission measurements with optical simulations, and correlating the results with capacitance measurements, we are able to obtain a clear picture of the p-i-n situation and the EZ within the active layer of a sandwich-type LEC during operation. It is found that the p-doped zone grows to the center of the active layer while the EZ stays closer to the metal electrode and is unchanged over time. Furthermore, optical simulations reveal that the determined EZ limits the external quantum efficiency of the LEC by outcoupling efficiencies of less than 10%.

Hai-Ching Su

ChemPlusChem 83, 197 (2018)

DOI: 10.1002/cplu.201700455

Konrad Domanski, Essa A. Alharbi, Anders Hagfeldt, Michael Grätzel and Wolfgang Tress

Nature Energy 3, 61 (2018)

https://www.nature.com/articles/s41560-017-0060-5

Description:

The authors investigate the effects of different environmental factors and electrical load on the ageing behaviour of perovskite solar cells. They also demonstrate how the results of the experiments can be distorted and how to avoid the common pitfalls.

Xin Song, Nicola Gasparini, and Derya Baran

Advanced Electronic Materials 4,1700358 (2018)

DOI: 10.1002/aelm.201700358

Nobuhiro Nakamura, Junghwan Kim, Koji Yamamoto, Satoru Watanabe, and Hideo Hosono

Organic Electronics 51, 103 (2017)

10.1016/j.orgel.2017.09.016

Mohammed F. Al-Mudhaffera, Matthew J. Griffith, Krishna Feron, Nicolas C. Nicolaidis, Nathan A. Cooling, Xiaojing Zhou, John Holdsworth, Warwick J. Belcher, Paul C. Dastoor

Solar Energy Materials and Solar Cells 175, 77 (2018)

http://dx.doi.org/10.1016/j.solmat.2017.09.007

Kai-Ming Chiang, Bo-Wei Hsu, Yi-An Chang, Lin Yang, Wei-Lun Tsai, and Hao-Wu Lin

ACS Applied Materials & Interfaces 9, 40516 (2017)

https://doi.org/10.1021/acsami.7b12805

Abstract:In this work, a sequential vacuum deposition process of bright, highly crystalline, and smooth methylammonium lead bromide and phenethylammonium lead bromide perovskite thin films are investigated and the first vacuum-deposited organometallic halide perovskite light-emitting devices (PeLEDs) are demonstrated. Exceptionally low refractive indices and extinction coefficients in the emission wavelength range are obtained for these films, which contributed to a high light out-coupling efficiency of the PeLEDs. By utilizing these perovskite thin films as emission layers, the vacuum-deposited PeLEDs exhibit a very narrow saturated green electroluminescence at 531 nm, with a spectral full width at half-maximum bandwidth of 18.6 nm, a promising brightness of up to 6200 cd/m2, a current efficiency of 1.3 cd/A, and an external quantum efficiency of 0.36%.

ung-Yu Li, Shih-Pu Chen, Huei-Jhen Siao, Jin-Han Wu, Guan-Yu Chen, Cheng-Chang Chen, Shu-Yi Ho, Yi-Ping Lin, Hong-Hui Hsu, Jin-Sheng Lin, Ming-Shan Jeng, Nai-Chuan Chen, Hui-Kai Zeng, and Jenh-Yih Juang

Appl. Phys. Lett. 111, 093301 (2017)

doi: 10.1063/1.5000499

Yea-Fen Jang, Tzu-Chun Lin, Jhih-Yan Guo, Chien-Ming Fan Chiang, Ming-Lun Wu, Hsin-Yi Shen, Tsung-Cheng Chen, Zu-Po Yang, Ya-Ju Lee, Hai-Ching Su, Chih-Hao Chang, Shun-Wei Liu

Organic Electronics, 2017, 51, 129

https://doi.org/10.1016/j.orgel.2017.09.024

Long Ye, Yuan Xiong, Sunsun Li, Masoud Ghasemi, Nrup Balar, Johnathan Turner, Abay Gadisa, Jianhui Hou, Brendan T. O’Connor, and Harald Ade

Advanced Functional Materials 27,1702016 (2017)

DOI: 10.1002/adfm.201702016

Takeshi Gotanda, Shigehiko Mori, Haruhi Oooka, Hyangmi Jung, Hideyuki Nakao, Kenji Todori, and Yutaka Nakai

Journal of Materials Research 32,2700 (2017)

DOI: 10.1557/jmr.2017.264

Abstract:

Perovskite solar cells are promising for realizing high power conversion efficiency (PCE) with low manufacturing costs, but efficient coating methods are needed for commercialization. Here, a gas blowing method was used to fabricate perovskite solar cells and was found to create a smooth perovskite layer and to prevent voids in large-area cells, when organic materials were used as scaffolds for forming the perovskite. A PCE of 13% in a 1 cm2 active area is achieved by tuning the band-gap energy of MAPbX3 via substitution of Br for I ions in X sites. Incorporation of a poly(3,4-ethylenedioxythiophene) hole transport layer with a higher work function increased the open circuit voltage of the solar cells. All layers of the cells were fabricated at low temperatures (,140 °C), which makes it possible to incorporate a polymer substrate for producing flexible solar cells and high-throughput fabrication.

C Kirsch, S Altazin, R Hiestand, T Beierlein, R Ferrini, T Offermans, L Penninck, B Ruhstaller

Int. Jnl. of Multiphysics Volume 11 · Number 2 · 2017

S. Olivier, E. Ishow, S. Meunier Della-Gatta, T. Maindron

Organic Electronics 49, 24 (2017)

DOI: 10.1016/j.orgel.2017.06.017

S. Jenatsch, L. Wang, N. Leclaire, E. Hack, R. Steim, S.B. Anantharaman, J. Heier, B. Ruhstaller, L. Penninck, F. Nüesch, R. Hany

Organic Electronics 48, 77 (2017),

doi: 10.1016/j.orgel.2017.05.038.

Marco Natali, Santiago D. Quiroga, Luca Passoni, Luigino Criante, Emilia Benvenuti, Gabriele Bolognini, Laura Favaretto, Manuela Melucci, Michele Muccini, Francesco Scotognella, Fabio Di Fonzo, and Stefano Toffanin

Adv. Funct. Mater. 2017, 1605164

DOI: 10.1002/adfm.201605164

Amin Salehi, Szuheng Ho, Ying Chen, Cheng Peng, Hartmut Yersin, and Franky So

Adv. Optical Mater. 2017, 1700197

DOI: 10.1002/adom.201700197

Chul Woong Joo, Keunsoo Lee, Jonghee Lee, Hyunsu Cho, Jin-Wook Shin, Nam Sung Cho, Jaehyun Moon

Journal of Luminescence 187 (2017) 433–440

https://dx.doi.org/10.1016/j.jlumin.2017.03.057

T. Lanz, E. M. Lindha and L. Edmana

Journal of Materials Chemistry C 5, 4706 (2017)

DOI: 10.1039/C7TC01022B

Martin Thomas Neukom, Simon Züfle, Evelyne Knapp, Mohammed Makha, Roland Hany, Beat Ruhstaller

Solar Energy Materials and Solar Cells 169 (2017) 159–166

https://doi.org/10.1016/j.solmat.2017.05.021

Abstract:There is increasing evidence that the presence of mobile ions in perovskite solar cells can cause a current-voltage curve hysteresis. However, it is still the subject of ongoing debates on how exactly mobile ions influence the device operation. We use drift-diffusion simulations incorporating mobile ions to describe IV curves of preconditioned methylammonium lead iodide perovskite solar cells and compare them with experimental results. Our simulation results show that the hysteresis depends on the extent of surface recombination and on the diffusion length of charge carriers. We provide a detailed explanation for the reduced hysteresis of perovskite solar cells with high power conversion efficiencies. We find that in high-efficiency solar cells ion migration is still present, but does not cause a hysteresis effect. In these devices, charge extraction is mainly driven by the diffusion of free electrons and holes.

Jan A. Mayer, Benjamin Gallinet, Ton Offermans, Igor Zhurminsky, Rolando Ferrini

Solar Energy Materials & Solar Cells 163 (2017) 51–57

DOI: http://dx.doi.org/10.1016/j.solmat.2017.01.015

D. H. Kim, K. Inada, L. Zhao, T. Komino, N. Matsumoto, J. C. Ribierre, and C. Adachi

J. Mater. Chem. C 5,1216 (2017)

DOI: 10.1039/C6TC04786F

S. Altazin, L. Stepanova, K. Lapagna, P. Losio, J. Werner, B. Niesen, A. Dabirian, M. Morales-Masis, S. de Wolf, C. Ballif, B. Ruhstaller

32nd European Photovoltaic Solar Energy Conference and Exhibition, pp 1276 - 1279 , 2016

https://doi.org/10.4229/EUPVSEC20162016-3DV.2.2

S. Altazin, S. Züfle, E. Knapp, C. Kirsch, T.D. Schmidt, L. Jäger, Y. Noguchi, W. Brütting, B. Ruhstaller

Organic Electronics 39 (2016) 244-249

https://dx.doi.org/10.1016/j.orgel.2016.10.014

Hyunsu Cho, Chul Woong Joo, Jonghee Lee, Hyunkoo Lee,Jaehyun Moon, Jeong-IK Lee, Jun Yeob Lee, Youngjin Kang andNam Sung Cho

Optics Express 24, 24161 (2016)

https://dx.doi.org/10.1364/OE.24.024161

Martin Neukom,

Msc Thesis, Jan 2016.arXiv:1611.06425 [cond-mat.mtrl-sci]download PDF

Abstract:Transient opto-electrical measurements of methylammonium lead iodide (MALI) perovskite solar cells (PSCs) are performed and analyzed in order to elucidate the operating mechanisms. The current response to a light pulse or voltage pulse shows an extraordinarily broad dynamic range covering 9 orders of magnitude in time – from microseconds to minutes – until steady-state is reached. Evidence of a slowly changing charge density at the perovskite layer boundaries is found, which is most probably caused by mobile ions.

Currentvoltage curves (IV curves) are measured with very fast scan-rate after keeping the cell for several seconds at a constant voltage as proposed by Tress et al. Numerical drift-diffusion simulations reproduce the measured IV curves using different distributions of ions in the model. Analysing the band diagram of the simulation result sheds light on the operating mechanism.

To further investigate the effects at short time scales (below milliseconds) photo-generated charge extraction by linearly increasing voltage (photo-CELIV) experiments are performed. We postulate that mobility imbalance in combination with deep hole trapping leads to dynamic doping causing effects from microseconds to milliseconds. Comprehensive transient drift-diffusion simulations of the photo-CELIV experiments strengthen this hypothesis.

This advanced characterization approach combining dynamic response measurements and numerical simulations represents a key step on the way to a comprehensive understanding of device working mechanisms in emerging perovskite solar cells.

Serkan Esiner, Gijs W. P. van Pruissen, Martijn M. Wienk and René A. J. Janssen

J. Mater. Chem. A, 2016,4, 5107-5114

DOI: 10.1039/C5TA10459A

Lin-Song Cui, Shi-Bin Ruan, Fatima Bencheikh, Ryo Nagata, Lei Zhang, Ko Inada, Hajime Nakanotani, Liang-Sheng Liao & Chihaya Adachi

Nature Communications, 2017, 8, 2250

DOI: 10.1038/s41467-017-02419-x

Monica Morales-Masis, Stefaan De Wolf, Rachel Woods-Robinson, Joel W. Ager, and Christophe Ballif

Adv. Electron. Mater. 2017, 1600529

https://dx.doi.org/10.1002/aelm.201600529

Simon Züfle, Stéphane Altazin, Alexander Hofmann, Lars Jäger, Martin T. Neukom, Tobias D. Schmidt, Wolfgang Brütting, Beat Ruhstaller,

J. Appl. Phys. 121, 175501, 2017.

https://doi.org/10.1063/1.4982903

Abstract:We demonstrate the application of the CELIV (charge carrier extraction by linearly increasing voltage) technique to bilayer organic light-emitting devices (OLEDs) in order to selectively determine the hole mobility in N,N0-bis(1-naphthyl)-N,N0-diphenyl-1,10-biphenyl-4,40-diamine (a-NPD). In the CELIV technique, mobile charges in the active layer are extracted by applying a negative voltage ramp, leading to a peak superimposed to the measured displacement current whose temporal position is related to the charge carrier mobility. In fully operating devices, however, bipolar carrier transport and recombination complicate the analysis of CELIV transients as well as the assignment of the extracted mobility value to one charge carrier species. This has motivated a new approach of fabricating dedicated metal-insulator-semiconductor (MIS) devices, where the extraction current contains signatures of only one charge carrier type. In this work, we show that the MIS-CELIV concept can be employed in bilayer polar OLEDs as well, which are easy to fabricate using most common electron transport layers (ETLs), like Tris-(8-hydroxyquinoline)aluminum (Alq3). Due to the macroscopic polarization of the ETL, holes are already injected into the hole transport layer below the built-in voltage and accumulate at the internal interface with the ETL. This way, by a standard CELIV experiment only holes will be extracted, allowing us to determine their mobility. The approach can be established as a powerful way of selectively measuring charge mobilities in new materials in a standard device configuration.

S. Züfle, S. Altazin, A. Hofmann, L. Jäger, M. T. Neukom, W. Brütting, and B. Ruhstaller

J. Appl. Phys. 122, 115502, 2017.

https://dx.doi.org/10.1063/1.4992041

Abstract: Charge carrier transport in organic semiconductor devices is thermally activated with characteristic activation energies in the range of 0.2–0.6 eV, leading to strongly temperature-dependent behavior. For designing efficient organic semiconductor materials and devices, it is, therefore, indispensable to understand the origin of these activation energies. We propose that in bilayer organic light-emitting diodes (OLEDs) employing a polar electron transport layer, as well as in metal-insulator-semiconductor (MIS) devices, the hole injection barrier Einj and the hole mobility activation energy El can be decoupled from each other if temperature-dependent capacitance frequency (C-f-T) and MIS-CELIV (charge extraction by linearly increasing voltage) experiments are combined. While the C-f-T signal contains information of both injection and transport, the CELIV current is expected to be insensitive to the electrode injection properties. We employ numerical drift-diffusion simulations to investigate the accuracy of this analytical parameter extraction approach and to develop criteria for its validity. We show that the implicit assumption of constant charge density and field profiles leads to systematic errors in determining the activation energies. Thus, one should be aware of the intrinsic limitations of the analytical Arrhenius fit, and for more accurate parameter determination full drift-diffusion modeling is advised. Applying the analytical method to a standard bilayer OLED, we find that the total activation energy of 0.5 eV for the hole current can be split into contributions of 0.25 eV each for injection barrier and mobility. Finally, we also discuss the broader applicability of this method for other device stacks and material combinations.

Donatas Gesevicius, Antonia Neels, Sandra Jenatsch, Erwin Hack, Lucas Viani, Stavros Athanasopoulos, Frank Nüesch, and Jakob Heier

Advanced Science 5,1700496 (2018)

https://doi.org/10.1002/advs.201700496

L. Zhao, T. Komino, D. Hyeon Kim, M. Hasnan Sazzad, D. Pitrat, J.-C. Mulatier, C. Andraud, J.-C. Ribierre and C. AdachiJ. Mater. Chem. C, 2016, 4, 11557

https://doi.org/10.1039/C6TC02861F

H. Zhang, B. Niesen, E. Hack, S. Jenatsch, L. Wang, A. C. V
eron, M. Makha, R. Schneider, Y. Arroyo, R. Hany, F. Nüesch

Organic Electronics 30 (2016) 191-199

http://dx.doi.org/10.1016/j.orgel.2015.12.013

J. Mayer, B. Gallinet, T. Offermans and R. Ferrini

Optics Express 24, A358 (2016)

Doi:10.1364/oe.24.00a358

T. Komino, Y. Sagara, H. Tanaka, Y. Oki, N. Nakamura, H.Fujimoto, and C. Adachi

Applied Physics Letters 108, 241106 (2016)

doi: 10.1063/1.4954163

N. A. Cooling, E. F. Barnes, F. Almyahi, K. Feron, M. Al-Mudhaffer, A. Al-Ahmad, B. Vaughan , T. R. Andersen , M. J. Griffith , A. S. Hart , A. G. Lyons , W. J. Belcher , P. C. Dastoor

J. Mater. Chem. A 4, 10274 (2016)

DOI: 10.1039/C6TA04191D

S. Altazin, S. Züfle, E. Knapp, C. Kirsch, T.D. Schmidt, L. Jäger, W. Brütting, B. Ruhstaller

SID Digest of Technical Papers 47, 1750 (2016)

https://doi.org/10.1002/sdtp.11059

Shiho Oyama, Heisuke Sakai, and Hideyuki Murata

Japanese Journal of Applied Physics 55, 03DD13 (2016)

http://doi.org/10.7567/JJAP.55.03DD13

M. L. Inche Ibrahim

Journal Of Applied Physics 119, 154504 (2016)

DOI: http://dx.doi.org/10.1063/1.4946038

Sandra Jenatsch, Lei Wang, Matia Bulloni, Anna Christina Véron, Beat Ruhstaller, Stéphane Altazin, Frank Alain Nüesch, and Roland Hany

ACS Appl. Mater. Interfaces 8, 6554 (2016)

DOI: 10.1021/acsami.5b12055

Stéphane Altazin, Clément Reynaud, Ursula M. Mayer, Thomas Lanz, Kevin Lapagna, Reto Knaack, Lieven Penninck, Christoph Kirsch, Kurt P. Pernstich, Stephan Harkema, Dorothee Hermes, Beat Ruhstaller

SID Digest of Technical Papers 46, 564 (2015)

https://doi.org/10.1002/sdtp.10478

J.A. Bartelt , D. Lam , T. M. Burke , S. M. Sweetnam ,and M. D. McGehee

Advanced Energy Materials 2015, 5, 1500577

DOI: 10.1002/aenm.201500577

Chunhui Duan , Alice Furlan , Jacobus J. van Franeker , Robin E. M. Willems, Martijn M. Wienk , and René A. J. Janssen

Adv. Mater. 2015, 27, 4461–4468

DOI: 10.1002/adma.201501626

T. Lanz, K. Lapagna, S. Altazin, M. Boccard, F.J. Haug, C. Ballif, B. Ruhstaller

Optics Express 23 (11), A539-A546, (2015)

https://doi.org/10.1364/OE.23.00A539

Weiwei Li, Koen H. Hendriks, Alice Furlan, Martijn M. Wienk, and René A. J. Janssen

J. Am. Chem. Soc. 2015, 137, 2231−2234

DOI: 10.1021/ja5131897

R. Steim, P. Chabrecek, U. Sonderegger, B. Kindle-Hasse, W. Siefert, T. Kroyer, P. Reinecke, T. Lanz, T. Geiger, R. Hany and F. Nüesch

Appl. Phys. Lett. 106, 193301 (2015)

http://dx.doi.org/10.1063/1.4919940

Hironori Kaji, Hajime Suzuki, Tatsuya Fukushima, Katsuyuki Shizu, Katsuaki Suzuki, Shosei Kubo, Takeshi Komino, Hajime Oiwa, Furitsu Suzuki, Atsushi Wakamiya, Yasujiro Murata and Chihaya Adachi

Nature Communications 6, 8476 (2015)

https://doi.org/10.1038/ncomms9476

M. L. Inche Ibrahim, Zubair Ahmad, Khaulah Sulaiman

AIP Advances 5, 027115 (2015)

http://dx.doi.org/10.1063/1.4908036

M. Jahnel, B. Beyer, M. Thomschke, K. Fehse , F. Krujatzand K. Leo

Electronics 2015, 4, 982-994

doi:10.3390/electronics4040982

S. Züfle, M. T. Neukom, S. Altazin, M. Zinggeler, M. Chrapa, T. Offermans, B. Ruhstaller,

Adv. Energy Mater., 1500835, 2015.

https://doi.org/10.1002/aenm.201500835

Abstract:

In standard unencapsulated poly(3‐hexylthiophene):[6,6]‐phenyl C61‐butyric acid methyl ester solar cells exposed to humid air, the oxidation of the aluminum cathode is known to be a key degradation mechanism. Water that enters the device at the edges and through pinholes diffuses to the organic–electrode interface. The forming oxide acts as a thin insulating layer that gives rise to an injection/extraction barrier and leads to a loss in the device current. In order to understand this behavior in detail various steady‐state, transient, and impedance measurement techniques are performed in combination with drift‐diffusion simulations. With this combinatorial approach, the dominant degradation mechanism is confirmed to be the development of a blocking interface layer. This layer grows laterally leading to a loss in effective area due to the rapid local oxidation of the aluminum layer. Thus by combining multiple electrical techniques and optoelectrical simulations the dominant degradation mechanism can be evaluated. The same methodology is also beneficial for more stable and efficient novel solar cells.

Beatrice Beyer and Karl Leo

J. Mater. Chem. C, 2015, 3 , 10830

DOI: 10.1039/c5tc02446c

Stéphane Altazin, Kevin Lapagna, Thomas Lanz, Christoph Kirsch, Reto Knaack, Beat Ruhstaller

SID Digest of Technical Papers 45, 576 (2014)

https://doi.org/10.1002/j.2168-0159.2014.tb00151.x

M. R. Lenze, T. E. Umbach, C. Lentjes, K. Meerholz

Organic Electronics 15, 12, 3584-3589 (2014)

http://dx.doi.org/10.1016/j.orgel.2014.10.001

H. Zhang, A. Borgschulte, F. A. Castro, R. Crockett, A. C. Gerecke, O. Deniz, J. Heier, S. Jenatsch, F. Nüesch, C. Sanchez-Sanchez, A. Zoladek-Lemanczyk, R. Hany

Adv. Energy Mater, 5, 1400734 (2014)

https://doi.org/10.1002/aenm.201400734

T. Komino, H. Tanaka, C. Adachi

Chem. Mater., 26 (12), 3665–3671 (2014)

https://pubs.acs.org/doi/10.1021/cm500802p

D. Gupta, M. M. Wienk, R. A. J. Janssen

ACS Appl. Mater. Interfaces, 6 (16), 13937–13944 (2014)

ttps://pubs.acs.org/doi/10.1021/am503262e

S. Jenatsch, R. Hany, A.C. Véron, M. Neukom, S. Züfle, A. Borgschulte, B. Ruhstaller, F. Nüesch

J. Phys. Chem. C, 118 (30), 17036, 2014

https://pubs.acs.org/doi/10.1021/jp5005314

M. Eck, C.V. Phama, S. Züfle, M. Neukom, M. Seßler, D. Scheunemann, E. Erdem, S. Weber, H. Borchert, B. Ruhstaller, M. Krüger

Physical Chemistry Chemical Physics, 16 (24) 12251, 2014

https://dx.doi.org/10.1039/c4cp01566e

S. Zhang, Z. Liu, X. Wang, S. Yue, Z. Zhang, Q. Wu, G. Xie, Q. Xue, Y. Chen, P. Wang, R. Gu, D. Qu, Y. Zhao, S. Liu

Thin Solid Films 537, 221 (2013)

https://doi.org/10.1016/j.tsf.2013.04.036

J. Singh, M. Narayan

Nanoscience and Technology, 1(1), 8, 2013.

PDF

G. Liaptsis, K. Meerholz

Adv. Funct. Mater., 23, 359-365, 2013

https://doi.org/10.1002/adfm.201201197

B. Perucco, N.A. Reinke, D. Rezzonico, E. Knapp, S. Harkema, B. Ruhstaller

Organic Electronics 13, 1827 (2012)

https://doi.org/10.1016/j.orgel.2012.05.053

PDF

S. Zhang, G. Xie, Q. Xue, Z. Zhang, L. Zhao, Y. Luo, S. Yue, Y. Zhao, S. Liu

Thin Solid Films 520, 2966 (2012)

https://doi.org/10.1016/j.tsf.2011.10.148

M.T. Neukom, S. Züfle, B. Ruhstaller

Organic Electronics 13, 2910 (2012)

https://doi.org/10.1016/j.orgel.2012.09.008

PDF

E. Knapp, B. Ruhstaller

Journal of Applied Physics 112,024519 (2012)

https://doi.org/10.1063/1.4739303

PDF

V.S. Gevaerts, J.A. Koster, M.M. Wienk, R.A. Janssen

ACS Applied Materials & Interfaces 3, 9, 3252 (2011)

https://pubs.acs.org/doi/10.1021/am200755m

PDF

U. Hörmann, J. Wagner, M. Gruber, A. Opitz, W. Brütting

Physica Status Solidi Rapid Research Letters, 5, 241 (2011)

https://doi.org/10.1002/pssr.201105238

E. Knapp, B. Ruhstaller

Appl. Phys. Lett. 99, 9, 093304 (2011)

https://doi.org/10.1063/1.3633109

E. Knapp, B. Ruhstaller

Optical and Quantum Electronics, 42,667 (2011)

https://dx.doi.org/10.1007/s11082-011-9443-1

PDF

B. Ruhstaller, E. Knapp, B. Perucco, N. Reinke, D. Rezzonico and F. Müller

Optoelectronic Devices and Properties, Oleg Sergiyenko (Ed.)

ISBN 978-953-307-204-3, 2011

https://dx.doi.org/10.5772/14626

M. Neukom, N.A. Reinke, B. Ruhstaller

Solar Energy 85, 1250 (2011)

https://doi.org/10.1016/j.solener.2011.02.028

PDF

J. Hauss, T. Bocksrocker, B. Riedel, U. Lemmer, M. Gerken,

Optics Express 19, a851 (2011)

https://doi.org/10.1364/OE.19.00A851

D. Rezzonico, B. Perucco, E. Knapp, R. Häusermann, N.A. Reinke, F. Müller, B. Ruhstaller

Journal of Photonics for Energy, 1, 011005-1-11, 2011.

https://doi.org/10.1117/1.3528045

PDF

Yueh-Tsung Tsai, Kensuke Goto, Osamu Yoshikawa, Shogo Mori, Takashi Sagawa and Susumu Yoshikawa

Japanese Journal of Applied Physics 50 (2011) 01BC13

https://dx.doi.org/10.1143/JJAP.50.01BC13

Mark L. Hildner, Jonathan M. Ziebarth

SID Digest of Technical Papers 42,1764 (2011)

https://doi.org/10.1889/1.3621234

H. Jin , C. Tao , M. Velusamy , M. Aljada , Y. Zhang , M. Hambsch ,
P. L. Burn,  and P. Meredith

Advanced Mataterials24, p. 2572-2577 (2012)
DOI: 10.1002/adma.201104896

T. R. Andersen, F. Almyahi, N. A. Cooling, D. Elkington, L. Wiggins, A. Fahya, K. Feron, B. Vaughan, M. J. Griffith, A. J. Mozer, C. Saekung, G. G. Wallace, W. J. Belcher, and P. C. Dastoor.

Journal of Materials Chemistry A 4, 15986 (2016)

DOI: 10.1039/x0xx00000x

Markus Regnat

Dissertation, EFPL, 2019

https://infoscience.epfl.ch/record/270200?ln=en

The understanding of charge recombination and exciton dynamics and the determination of the position of light generation are essential for the fabrication of modern OLEDs and are the goal of this thesis. Therefore two different OLED types, phosphorescence-based OLEDs and state-of-the-art TADF exciplex host OLEDs incorporating a fluorescent emitter, are studied by electro-optical characterization and device modeling.

Robin E. M. Willems, Stefan C. J. Meskers, Martijn M. Wienk, and René A. J. Janssen

Nat. Photonics 13, 540–546 (2019)

https://www.nature.com/articles/s41566-019-0415-5

Materials that exhibit thermally activated delayed fluorescence are promising for the realization of efficient organic light-emitting diodes. However, finding suitable deep-blue thermally activated delayed fluorescence materials is still challenging. Here, we report two highly efficient deep-blue thermally activated delayed fluorescence emitters, TDBA–Ac and TDBA–DI, containing oxygen-bridged, symmetric and rigid boron acceptor moieties.

Robin E. M. Willems, Stefan C. J. Meskers, Martijn M. Wienk, and René A. J. Janssen

J. Phys. Chem. C 2019, 123, 16, 10253–10261

https://pubs.acs.org/doi/10.1021/acs.jpcc.9b00568

Singlet fission in pentacene creates two triplet excitons per absorbed photon. In a solar cell, each triplet can generate an electron–hole pair, and hence, external quantum efficiencies exceeding 100% have been reported for pentacene–fullerene solar cells. The energetics of this process are intriguing because the minimum photon energy loss, defined as the energy difference between the (triplet) exciton state and the open-circuit voltage, is less than 0.5 eV and distinctively smaller than that in most organic donor–acceptor solar cells. To investigate the energetics of this process, we analyze the effect of the energy of the lowest unoccupied molecular orbital (LUMO) for different fullerene derivatives.

Akmaral Seitkhan, Marios Neophytou, Mindaugas Kirkus, Edy Abou-Hamad,

Mohamed Nejib Hedhili, Emre Yengel, Yuliar Firdaus, Hendrik Faber, Yuanbao Lin,

Leonidas Tsetseris, Iain McCulloch, and Thomas D. Anthopoulos

Adv. Funct. Mater December 5, 2019, 1905810

DOI: 10.1002/adfm.201905810

A simple approach that enables a consistent enhancement of the electron extracting properties of the widely used small‐molecule Phen‐NaDPO and its application in organic solar cells (OSCs) is reported. It is shown that the addition of minute amounts of the inorganic molecule Sn(SCN)2 into Phen‐NaDPO improves both the electron transport and its film‐forming properties. Use of Phen‐NaDPO:Sn(SCN)2 blend as the electron transport layer (ETL) in binary PM6:IT‐4F OSCs leads to a remarkable increase in the cells' power conversion efficiency (PCE) from 12.6% (Phen‐NaDPO) to 13.5% (Phen‐NaDPO:Sn(SCN)2).

Thomas Ferschke, Alexander Hofmann, Wolfgang Brütting and Jens Pflaum

ACS Applied Electronic Materials 2020

https://dx.doi.org/10.1021/acsaelm.9b00687

Determining noninvasively the microscopic optoelectronic parameters of molecular assemblies would constitute an important achievement in material as well as in life sciences. In this contribution, we cope with this challenge by utilizing fluorescent tetraphenyldibenzoperiflanthene (DBP) molecules as optically addressable sensors deterministically positioned in N,NŒ-di(1-naphthyl)-N,NŒ-diphenyl-(1,1Œ- biphenyl)-4,4Œ-diamine/tris(8-hydroxyquinolato)aluminum (NPB/Alq3) organic light-emitting diodes (OLEDs) as a model system.

Markus Regnat, Kurt P. Pernstich, Kwon-Hyeon Kim, Jang-Joo Kim, Frank Nüesch, and Beat Ruhstaller

Adv. Electron. Mater. 1900804 (2019)

https://doi.org/10.1002/aelm.201900804

Fluorescence-based organic light-emitting diodes (OLEDs) using thermally activated delayed fluorescence (TADF) have increasingly attracted attention in research and industry. One method to implement TADF is based on an emitter layer composed of an exciplex host and a fluorescent dopant. Even though the experimental realization of this concept has demonstrated promising external quantum efficiencies, the full potential of this approach has not yet been assessed. To this end, a comprehensive electro-optical device model accounting for the full exciton dynamics including triplet harvesting and exciton quenching is presented. The model parameters are fitted to multiple output characteristics of an OLED comprising a TADF exciplex host with a fluorescent emitter, showing an external quantum efficiency of >10%. With the model at hand, an emission zone analysis and a parameter study are performed, and possible routes for further efficiency enhancement are presented.

Wei Li, Wenqi Li, Lin Gan, Mengke Li, Nan Zheng, Chengyun Ning, Dongcheng Chen, Yuan-Chun Wu, and Shi-Jian Su

ACS Appl. Mater. Interfaces 2020, 12, 2717-2723

http://dx.doi.org/10.1021/acsami.9b17585

A pivotal thermally activated delayed-fluorescence (TADF) emitter, DspiroAc-TRZ, was developed, and it exhibits greatly enhanced electroluminescence performance in nondoped organic light-emitting diodes (OLEDs) owing to the concurrent manipulation of aggregation behavior and monomolecular structure. The delicate nonplanar packing pattern in the DspiroAc-TRZ crystal can not only lead to highly efficient solid-state luminescence but also form a loose intermolecular packing pattern, greatly decreasing the HOMO or LUMO overlaps in dimers and shortening the triplet exciton diffusion length. In addition, the rigid donor and acceptor moieties in DspiroAc-TRZ can rigidify the molecular backbone, resulting in a tiny geometric vibrational relaxation in the excited state. Impressively, high photoluminescent quantum yields of 78.5 and 83.7% were achieved for the DspiroAc-TRZ single crystal and nondoped film. A high external quantum efficiency (EQE) of 25.7% was achieved in a nondoped sky-blue TADF OLED, which is higher than any reported EQE value of nondoped sky-blue TADF OLEDs so far.

Andrew S. Hart, Thomas R. Andersen, Matthew J. Griffith, Adam Fahy, Ben Vaughan, Warwick J. Belcher and Paul C. Dastoor

RSC Advances 2020

https://dx.doi.org/10.1039/c9ra08826a

Currently, large-scale roll-to-roll production of printed organic photovoltaics (OPVs) involves high-temperature annealing steps that are not compatible with thermally sensitive substrates, such as coated fabrics. In particular, the processing temperatures needed to produce the required crystalline ordering in the printed films are typically above the deformation and melting points of these substrates. In this paper, we investigate the use of local solvent recrystallization (solvent annealing) on the roll-to-roll scale as a method for avoiding high-temperature thermal annealing. Solvent annealing was performed by slot-die coating a mixture of chloroform and methanol over a previously printed P3HT ICXA active layer film. Peak device performance was found for the 30% chloroform/70% methanol annealing case which increased device performance by a factor of 4 over the not treated devices.

Alexander J.L. Hofmann, Simon Züfle, Kohei Shimizu, Markus Schmid, Vivien Wessels, Lars Jäger, Stéphane Altazin, Keitaro Ikegami, Motiur Rahman Khan, Dieter Neher, Hisao Ishii, Beat Ruhstaller, and Wolfgang Brütting

Physical Review Applied 12, 064052 (2019)

http://dx.doi.org/10.1103/PhysRevApplied.12.064052

If not oriented perfectly isotropically, the strong dipole moment of polar organic semiconductor materials such as tris-(8-hydroxyquinolate)aluminum (Alq3) will lead to the buildup of a giant surface potential (GSP) and thus to a macroscopic dielectric polarization of the organic film.

Sudhir Kumar, Jakub Jagielski, Tommaso Marcato, Simon F. Solari, and Chih-Jen Shih

J. Phys. Chem. Lett. 2019, 10, 24, 7560-7567

https://doi.org/10.1021/acs.jpclett.9b02950

There has been a tremendous amount of interest in developing high-efficiency light-emitting diodes (LEDs) based on colloidal nanocrystals (NCs) of hybrid lead halide perovskites. Here, we systematically investigate the ligand effects on EL characteristics by tuning the hydrophobicity of primary alkylamine ligands used in NC synthesis. By increasing the ligand hydrophobicity, we find (i) a reduced NC size that induces a higher degree of quantum confinement, (ii) a shortened exciton lifetime that increases the photoluminescence quantum yield, (iii) a lowering of refractive index that increases the light outcoupling efficiency, and (iv) an increased thin-film resistivity. Accordingly, ligand engineering allows us to demonstrate high-performance green LEDs exhibiting a maximum external quantum efficiency up to 16.2%. The device operational lifetime, defined by the time lasted when the device luminance reduces to 85% of its initial value, LT85, reaches 243 min at an initial luminance of 516 cd m–2.

Matthias Diethelm, Andreas Schiller, Maciej Kawecki, Andrius Devižis, Balthasar Blülle, Sandra Jenatsch, Evelyne Knapp, Quirin Grossmann, Beat Ruhstaller, Frank Nüesch, and Roland Hany

Advanced Functional Materials 1906803 (2019)

https://doi.org/10.1002/adfm.201906803

In light‐emitting electrochemical cells (LECs), the position of the emission zone (EZ) is not predefined via a multilayer architecture design, but governed by a complex motion of electrical and ionic charges. As a result of the evolution of doped charge transport layers that enclose a dynamic intrinsic region until steady state is reached, the EZ is often dynamic during turn‐on. For thick sandwich polymer LECs, a continuous change of the emission color provides a direct visual indication of a moving EZ. Results from an optical and electrical analysis indicate that the intrinsic zone is narrow at early times, but starts to widen during operation, notably well before the electrical device optimum is reached. Results from numerical simulations demonstrate that the only precondition for this event to occur is that the mobilities of anions and cations are not equal, and the direction of the EZ shift dictates mobilitycat > mobilityan. Quantitative ion profiles reveal that the displacement of ions stops when the intrinsic zone stabilizes, confirming the relation between ion movement and EZ shift. Finally, simulations indicate that the experimental current peak for constant‐voltage operation is intrinsic and the subsequent decay does not result from degradation, as commonly stated.

Sandra Jenatsch, Simon Züfle, Paul-Anton Will, Balthasar Blülle, Martin Neukom, Simone Lenk, Sebastian Reineke, Daniele Braga, Konrad Domanski, Beat Ruhstaller

SID 2019 Digest, P-176 (2019)

https://doi.org/10.1002/sdtp.13333

Single-carrier devices are perfect model systems to extract material parameters for more complex multilayer organic light-emitting diodes (OLEDs) and to learn about charge transport and injection properties of the device. By combining simulation and measurements in steady-state and frequency domain, we obtain a set of reliable material parameters which can be used to model the multilayer OLED structure. Moreover, we can also evaluate the contact behavior and conclude that the OLED operation is limited by electron transport.

Martin T. Neukom

Dissertation, University of Augsburg, 2019

https://opus.bibliothek.uni-augsburg.de/opus4/frontdoor/deliver/index/docId/63805/file/characterization_and_modelling_diss_neukom.pdf

Solar energy is one of the key enabling technologies for the transition to a zero-carbon society – a necessity to mitigate global climate change. Emerging photovoltaic technologies based on novel semiconductor materials offer new disruptive applications since they can be made light-weight, flexible and in arbitrary shape and colour. A novel step response technique illustrates that the retraction of ionic charges from layer interfaces enables charge transport.

Sungho Nam, Mujeeb Ullah Chaudhry, Kornelius Tetzner, Christopher Pearson, Chris Groves, Michael C. Petty, Thomas D. Anthopoulos, and Donal D. C. Bradley

ACS Photonics (2019)

https://doi.org/10.1021/acsphotonics.9b01265

Device characterization shows that the use of P(VDF-TrFE-CTFE) leads to larger channel currents (≈2 mA) and lower operating voltages (−35 V) than for previously reported polymer based OLETs. Furthermore, the combined transparency of the dielectric and gate electrode, results in efficient bottom emission with external quantum efficiency of ≈0.88% at a luminance L ≥ 2000 cd m–2. Importantly, the resulting OLETs exhibit excellent shelf life and operational stability. The present work represents a significant step forward in the pursuit of all-solution-processed OLET technology for lighting and display applications.

Jordi Sastre, Tzu-Ying Lin, Alejandro Nicolas Filippin, Agnieszka Priebe, Enrico Avancini, Johann Michler, Ayodhya N. Tiwari, Yaroslav E. Romanyuk, and Stephan Buecheler

ACS Appl. Energy Mater., (2019)

https://doi.org/10.1021/acsaem.9b01387

Garnet Li7La3Zr2O12 (LLZO) is a promising solid-state electrolyte due to its wide electrochemical stability window and high Li-ion conductivity. This electrolyte has potential to be employed in the form of thin films for solid-state batteries, a promising approach in the quest for safer batteries with higher energy densities at lower fabrication costs. In this study, we use a scalable cosputtering process to fabricate LLZO thin films with subsequent postannealing at a temperature of 700 °C, significantly below the sintering temperatures employed in ceramic pellet processing.

Thorsten E. Umbach, Stefan Röllgen, Stefan Schneider, Heike Klesper, Anne M. Umbach, Klaus Meerholz

Adv. Eng. Mater. (2019)

https://doi.org/10.1002/adem.201900897

Organic light‐emitting diodes (OLEDS) still suffer from limited outcoupling efficiencies. In this contribution, a novel technology for the enhancement of the outcoupling efficiency of OLED devices is presented. By means of electro‐spray deposition (ESD) the active hole‐transport layer (HTL) is modified to have a reduced effective refractive index due to its porosity. A green‐emitting stack is tailored to demonstrate this effect, whereas additional haze effects are to be prevented. The introduction of a low‐index HTL results in a more efficient light extraction by a factor of 1.05 showing excellent agreement between experiment and simulation.

Akmaral Seitkhan, Marios Neophytou, Mindaugas Kirkus, Edy Abou-Hamad, Mohamed Nejib Hedhili, Emre Yengel, Yuliar Firdaus, Hendrik Faber, Yuanbao Lin, Leonidas Tsetseris, Iain McCulloch, and Thomas D. Anthopoulos

Advanced Functional Materials 1905810 (2019)

https://doi.org/10.1002/adfm.201905810

A simple approach that enables a consistent enhancement of the electron extracting properties of the widely used small-molecule Phen-NaDPO and its application in organic solar cells (OSCs) is reported. It is shown that addition of minute amounts of the inorganic molecule Sn(SCN)2 into Phen-NaDPO improves both the electron transport and its film-forming properties. Use of Phen-NaDPO:Sn(SCN)2 blend as the electron transport layer (ETL) in binary PM6:IT-4F OSCs leads to a remarkable increase in the cells’ power conversion efficiency (PCE) from 12.6% (Phen-NaDPO) to 13.5% (Phen-NaDPO:Sn(SCN)2). Combining the hybrid ETL with the best-in-class organic ternary PM6:Y6:PC70BM systems results to a similarly remarkable PCE increase from 14.2% (Phen-NaDPO) to 15.6% (Phen-NaDPO:Sn(SCN)2). The consistent PCE enhancement is attributed to reduced trap-assisted carrier recombination at the bulk-heterojunction/ETL interface due to the presence of new energy states formed upon chemical interaction of Phen-NaDPO with Sn(SCN)2. The versatility of this hybrid ETL is further demonstrated with its application in perovskite solar cells for which an increase in the PCE from 16.6% to 18.2% is also demonstrated.

Yan-Zhi Chen, Dian Luo, Chi-Haw Hsiang, Rong-Huei Yi, Ching-Hsuan Lin, Chin-Wei Lu, Shun-Wei Liu, Chih-Hao Chang, Hai-Ching Su

Organic Electronics (2019)

https://doi.org/10.1016/j.orgel.2019.105515

Enhancing device efficiencies of the blue and white light-emitting electrochemical cells (LECs) is realized by employing substrates with embedded diffusive layers containing scattering TiO2 nanoparticles (NPs). The diffusive layers can eliminate the influence of microcavity effect on the output electroluminescence (EL) spectrum and recover the intrinsic EL spectrum of the emissive layer. The emission zone positions of the blue and white LECs are estimated by fitting the measured EL spectra with the simulated EL spectra based on precisely tuned emission zone positions. Incorporating red-emitting guest dopant in the white LEC results in shifted emission zone toward the cathode due to enhanced electron trapping. 

Marios Neophytou, Michele De Bastiani, Nicola Gasparini, Erkan Aydin, Esma Ugur, Akmaral Seitkhan, Floriana Moruzzi, Yasmin Choaie, Alexandra J. Ramadan, Joel R. Troughton, Rawad Hallani, Achilleas Savva, Leonidas Tsetseris, Sahika Inal, Derya Baran, Frédéric Laquai, Thomas D. Anthopoulos, Henry J. Snaith, Stefaan De Wolf, and Iain McCulloch

ACS Appl. Energy Mater. (2019)

https://doi.org/10.1021/acsaem.9b01567

Charge transport layers strongly influence the performance of perovskite solar cells (PSCs). To date, compact layers and mesoporous scaffolds of titanium dioxide have emerged as good electron transport layers (ETL), enabling record power conversion efficiencies (PCE). However, these ETLs require sintering above 400 ¡ãC, which excludes them from low-temperature applications such as flexible devices and silicon-heterojunction tandems. Furthermore, instability of TiO2 under prolonged exposure to sunlight appears to be a critical issue. Here, we present the promising characteristics of low-temperature processed strontium titanate (STO) as an ETL to realize PSCs with 19% PCE. STO is a wide bandgap transparent inorganic perovskite. Compared with other low-temperature processed interlayers, STO reduces the parasitic absorption in the ultraviolet and visible range, improves the electron transport, and greatly increases the stability of the devices, retaining ¡«80% of their initial efficiency after 1000 h of constant white light illumination.

Xiang Xu, Jingyang Xiao, Guichuan Zhang, Long Wei, Xuechen Jiao, Hin-Lap Yip, Yong Cao

Science Bulletin (2019)

https://doi.org/10.1016/j.scib.2019.10.019

Interfacial modification of ZnO electron transparent layer with a fullerene self-assembled monolayer can simultaneously improve the efficiency and photo-stability of organic solar cells by improving the charge extraction property and stabilizing the active layer morphology, leading to a state-of-the-art organic solar cell with extrapolated lifetime more than 20 years.

Moulay Ahmed Slimani

Masterthesis, Universite de Quebec, 2019

http://espace.etsmtl.ca/2415/

Based on current energy and environmental context, research in the photovoltaic field is growing very fast. Silicon photovoltaic (PV) cells dominate the world market. One of the reasons limiting the efficiency of silicon-based solar cells are the losses due to thermalization. multi-junction cells represent a solution to reduce these losses, but they are expensive too. The printing technique, therefore represents a viable alternative for it is a low temperature and a low-cost technique. Moreover, it can be realized on flexible devices and with unlimited raw material. The objectives of this thesis are thus to firstly realize perovskite solar cells using the Slot Die printing technique and then to optimize it to optimize a 4-terminal (4T) tandem silicon/perovskite cell. A simulation study by SETFOS (Semiconducting Emission Thin Film Optics Simulation) was made to understand and optimize the effect of thickness, mobility of charge carriers and bands energy on the efficiency of the perovskite solar cell. Then, a characterization of the absorption coefficient of other layers inside the cells were made using Lambda 750 UV / Vis / NIR and X-ray diffraction technique (XRD) were used to optimize the temperature and the annealing time of the perovskite film. The last part of this work was reserved to the study of the effects of the layers of the perovskite cell on the absorption of the mono-crystalline silicon cell. This experimental study allowed us to optimize the layers of the perovskite solar cell and to evaluate the feasibility of having a perovskite/silicon tandem solar cell.

Seong Keun Kim, Raju Lampande, and Jang Hyuk Kwon

ACS Photonics (2019)

https://doi.org/10.1021/acsphotonics.9b01155

Abstract:

To attain high efficiency and stability in a top-emission organic light-emitting diode (TEOLED), the semitransparent metal cathode must have high transmittance, low absorbance, and uniform surface properties under continuous driving conditions. However, conventional semitransparent metal electrodes have numerous fundamental issues. Here, we report an electro-optically efficient and stable semitransparent pristine thin Ag cathode configuration for the high performances of TEOLED. 

Yuanbao Lin, Begimai Adilbekova, Yuliar Firdaus, Emre Yengel, Hendrik Faber, Muhammad Sajjad, Xiaopeng Zheng, Emre Yarali, Akmaral Seitkhan, Osman M. Bakr, Abdulrahman El-Labban, Udo Schwingenschlögl, Vincent Tung, Iain McCulloch, Frédéric Laquai, and Thomas D. Anthopoulos

Advanced Materials 1902965 (2019)

https://doi.org/10.1002/adma.201902965

Abstract:

The application of liquid‐exfoliated 2D transition metal disulfides (TMDs) as the hole transport layers (HTLs) in nonfullerene‐based organic solar cells is reported. It is shown that solution processing of few‐layer WS2 or MoS2 suspensions directly onto transparent indium tin oxide (ITO) electrodes changes their work function without the need for any further treatment. HTLs comprising WS2 are found to exhibit higher uniformity on ITO than those of MoS2 and consistently yield solar cells with superior power conversion efficiency (PCE), improved fill factor (FF), enhanced short‐circuit current (JSC), and lower series resistance than devices based on poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) and MoS2. Cells based on the ternary bulk‐heterojunction PBDB‐T‐2F:Y6:PC71BM with WS2 as the HTL exhibit the highest PCE of 17%, with an FF of 78%, open‐circuit voltage of 0.84 V, and a JSC of 26 mA cm−2. Analysis of the cells' optical and carrier recombination characteristics indicates that the enhanced performance is most likely attributed to a combination of favorable photonic structure and reduced bimolecular recombination losses in WS2‐based cells. The achieved PCE is the highest reported to date for organic solar cells comprised of 2D charge transport interlayers and highlights the potential of TMDs as inexpensive HTLs for high‐efficiency organic photovoltaics.

Miaosheng Wang, Yi-Hsuan Huang, Kai-Siang Lin, Tzu-Hung Yeh, Jiashun Duan, Tzu-Yu Ko, Shun-Wei Liu, Ken-Tsung Wong, and Bin Hu

Advanced Materials, 1904114 (2019)

https://doi.org/10.1002/adma.201904114

Experimental studies to reveal the cooperative relationship between spin, energy, and polarization through intermolecular charge‐transfer dipoles to harvest nonradiative triplets into radiative singlets in exciplex light‐emitting diodes are reported. Magneto‐photoluminescence studies reveal that the triplet‐to‐singlet conversion in exciplexes involves an artificially generated spin‐orbital coupling (SOC). The photoinduced electron parametric resonance measurements indicate that the intermolecular charge‐transfer occurs with forming electric dipoles (D+•→A−•), providing the ionic polarization to generate SOC in exciplexes.

Yingying Zhang, Xiong Li, Tingting Dai, Wentao Ha, Hongyu Du, Shuai Li, Kang Wang, Fanwen Meng, Denghui Xu, and Aicong Geng

J. Phys. Chem. C 123, 24446 (2019)

https://doi.org/10.1021/acs.jpcc.9b08242

Victoria Wißdorf, Markus Frericks, Michael Tzschoppe, Paula Connor, Sebastian Beck, Christof Pflumm, Annemarie Pucci, Wolfram Jaegermann, and Eric Mankel

ACS Appl. Electron. Mater. 1, 1994 (2019)

https://doi.org/10.1021/acsaelm.9b00279

Balthasar Blülle, Stéphane Altazin, Bérengère Frouin, Lidia Stepanova, Sandra Jenatsch, Beat Ruhstaller

SID 2019 DIGEST 50, 407 (2019)

https://doi.org/10.1002/sdtp.13285

Quantum dot (QD) enhanced LCDs are among today’s best-inclass displays exhibiting high brightness and large color gamut. In this presentation we focus on the underlying key mechanism of the embedded QD films, the down-conversion of light, and explore the optical characteristics of a state-of-the-art perovskite QD film by measuring its down-converting properties as a function of the viewing angle. The good agreement of the experimental results with simulations of the QD film indicates that computer aided parameter optimization can be key tool for engineering QD displays.

Safakath Karuthedath, Yuliar Firdaus, Ru-Ze Liang, Julien Gorenflot, Pierre M. Beaujuge, Thomas D. Anthopoulos, and Frédéric Laquai

Advanced Energy Materials 9, 1901443 (2019)

https://doi.org/10.1002/aenm.201901443

Martin T. Neukom, Andreas Schiller, Simon Züfle, Evelyne Knapp, Jorge Ávila, Daniel Pérez-del-Rey, Chris Dreessen, Kassio P.S. Zanoni, Michele Sessolo, Henk J. Bolink, Beat Ruhstaller

ACS Applied Materials and Interfaces 11, 23320 (2019)

https://pubs.acs.org/doi/10.1021/acsami.9b04991

A variety of experiments on vacuum-deposited methylammonium lead iodide perovskite solar cells are presented, including JV curves with different scan rates, light intensity-dependent open-circuit voltage, impedance spectra, intensity-modulated photocurrent spectra, transient photocurrents, and transient voltage step responses. All these experimental data sets are successfully reproduced by a charge drift-diffusion simulation model incorporating mobile ions and charge traps using a single set of parameters. While previous modeling studies focused on a single experimental technique, we combine steady-state, transient, and frequency-domain simulations and measurements. Our study is an important step toward the quantitative simulation of perovskite solar cells, leading to a deeper understanding of the physical effects of these materials. The analysis of the transient current upon voltage turn-on in the dark reveals that the charge injection properties of the interfaces are triggered by the accumulation of mobile ionic defects. We show that the current rise of voltage step experiments allows for conclusions about the recombination at the interface. Whether one or two mobile ionic species are used in the model has only a minor influence on the observed effects. A delayed current rise observed upon reversing the bias from +3 to -3 V in the dark cannot be reproduced yet by our drift-diffusion model. We speculate that a reversible chemical reaction of mobile ions with the contact material may be the cause of this effect, thus requiring a future model extension. A parameter variation is performed in order to understand the performance-limiting factors of the device under investigation.

Min-Geun Song, Kwan-Soo Kim, Hye In Yang, Seong Keun Kim, Jae-Hyun Kim, Chang-Wook Han, Hyun-Chul Choi, Ramchandra Pode, Jang Hyuk Kwon

Organic Electronics 76, 105418 (2019)

https://doi.org/10.1016/j.orgel.2019.105418

Toshinori Matsushima, Fatima Bencheikh, Takeshi Komino, Matthew R. Leyden, Atula S. D. Sandanayaka, Chuanjiang Qin and Chihaya Adachi

Nature 572, 502 (2019)

https://doi.org/10.1038/s41586-019-1435-5

We show that extraordinarily thick OLEDs can be fabricated by using the organic-inorganic perovskite methylammonium lead chloride, CH3NH3PbCl3 (MAPbCl3), instead of organics as the transport layers. Because MAPbCl3 films have high carrier mobilities and are transparent to visible light, we were able to increase the total thickness of MAPbCl3 transport layers to 2,000 nanometres—more than ten times the thickness of standard OLEDs—without requiring high voltage or reducing either internal electroluminescence quantum efficiency or operational durability. These findings will contribute towards a higher production yield of high-quality OLEDs, which may be used for other organic devices, such as lasers, solar cells, memory devices, and sensors.

R. Meitzner, M.Manceau, P. Troshin, F. Brunetti, G. Polino, Ulrich S. Schubert, M.Lira-Cantu, H.Hoppe

Solar Energy Materials and Solar Cells 202, 110151 (2019)

https://doi.org/10.1016/j.solmat.2019.110151

A cooperative study conducted between different laboratories to investigate organic solar cell degradation with respect to P3HT material properties and different solar cell architectures. Some materials properties were found to be more important than others for obtaining long lifetimes and high stability of P3HT-based polymer solar cells.

Yong Cui, Yuming Wang, Jonas Bergqvist, Huifeng Yao, Ye Xu, Bowei Gao, Chenyi Yang, Shaoqing Zhang, Olle Inganäs, Feng Gao and Jianhui Hou

Nature Energy 4, 768 (2019)

https://doi.org/10.1038/s41560-019-0448-5

Eric A. Margulies, Pierre-Luc T. Boudreault, Vadim I. Adamovich, Bert D. Alleyne, Michael S. Weaver, Julie J. Brown

SID 2019 DIGEST

https://doi.org/10.1002/sdtp.13072

Yong Cui, Huifeng Yao, Jianqi Zhang, Tao Zhang, Yuming Wang, Ling Hong, Kaihu Xian, Bowei Xu, Shaoqing Zhang, Jing Peng, Zhixiang Wei, Feng Gao & Jianhui Hou

Nature Communications 10, 2515 (2019)

https://doi.org/10.1038/s41467-019-10351-5

Rohit Ashok Kumar Yadav, Deepak Kumar Dubey, Sun-Zen Chen, Sujith Sudheendran Swayamprabha, Tzu-Wei Liang, Jwo-Huei Jou

MRS Advances, 2018, 3, 3445

https://doi.org/10.1557/adv.2018.365

Alessia Senes, Stefan C. J. Meskers, Wijnand M. Dijkstra, Jacobus J. van Franeker, Stéphane Altazin, Joanne S. Wilson and René A. J. Janssen

J. Mater. Chem. C, 2016, 4, 6302

https://doi.org/10.1039/c5tc03481g

Masaki Tanaka, Hiroki Noda, Hajime Nakanotani, and Chihaya Adachi

Appl. Phys. Lett. 116, 023302 (2020)

https://aip.scitation.org/doi/10.1063/1.5140210

Control of the molecular orientation in a glassy film is a crucial issue for the enhancement of the performance of organic light-emitting diodes (OLEDs). The authors are studying the molecular orientation in co-deposited films composed of a host molecule and a disk-shaped emitter that exhibits thermally activated delayed fluorescence is investigated systematically. It is found that the orientation of the transition dipole moment (TDM) of the disk-shaped emitters is strongly dependent on the glass transition temperature and the polarization of the host molecules. An almost perfectly horizontal orientation of the TDM of the disk-shaped emitters can be realized.

S. Karuthedath, J. Gorenflot, A. Melianas, Z. Kan, M. Kemerink, and F. Laquai

J. Phys. Chem. Lett. 2020, 11, 2838−2845

https://pubs.acs.org/doi/10.1021/acs.jpclett.0c00756

Determining the density of the triplet-state population in an organic solar cell is challenging. The authors employed transient absorption (TA) spectroscopy on the quinoxaline− thiophene copolymer TQ1 blended with PC71BM, quantify the transient charge and triplet-state densities, and parametrize their generation and recombination dynamics. They demonstrated that triplets are formed by both geminate and nongeminate recombination of charge carriers and decay primarily by triplet−triplet annihilation.

Yuliar Firdaus, Carr Hoi Yi Ho, Yuanbao Lin, Emre Yengel, Vincent M. Le Corre, Mohamad I. Nugraha, Emre Yarali, Franky So, Thomas D. Anthopoulos

ACS Energy Lett. 2020, 5, 12, 3692–370

https://pubs.acs.org/doi/10.1021/acsenergylett.0c02077

This paper demonstrates how to simulate and optimize double and triple-junction solar cells with an efficiency of 16.5% and 14.9%, respectively. Setfos was used by the research team to perform JV simulations to reproduce their measurements and in turn, analyse limitations and suggest potential improvements.

T. Gahlmann, K. O. Brinkmann, T. Becker, C. Tückmantel, C. Kreusel, F. van gen Hassend, S. Weber, and T. Riedl

Adv. Energy Mater. 2020, 1903897

https://onlinelibrary.wiley.com/doi/full/10.1002/aenm.201903897

The authors show that impermeable electron transport layers (ETLs) enable the deposition of semitransparent AgNW electrodes from green aqueous dispersions on top of the perovskite cell without damage. Ultimately, semitransparent PSCs are demonstrated that provide an efficiency of 17.4%, which is the highest efficiency of semitransparent p-i-n perovskite solar cells with an AgNW top electrode.

Jordi Sastre, Agnieszka Priebe, Max Döbeli, Johann Michler, Ayodhya N. Tiwari, and Yaroslav E. Romanyuk

Adv. Mater. Interfaces 2020, 7, 2000425

https://onlinelibrary.wiley.com/doi/full/10.1002/admi.202000425

The high ionic conductivity and wide electrochemical stability of the lithium garnet Li7La3Zr2O12 (LLZO) make it a viable solid electrolyte for all-solid-state lithium batteries with superior capacity and power densities. Fabrication of LLZO films has nonetheless been challenging because of lithium losses and the formation of impurity phases. The authors are presenting here a scalable method for fabricating submicron films of LLZO employing co-sputtering from doped LLZO and Li2O targets.

U. Aeberhard, R. Häusermann, A. Schiller, B. Blülle and B. Ruhstaller

2020 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), Turin, Italy, 2020, pp. 37-38

https://ieeexplore.ieee.org/document/9217773/

Description:

We present a comprehensive opto-electronic simulation framework for the computational analysis and optimization of perovskite-silicon tandem solar cells, consisting of a combination of a multiscale optical model for the simultaneous consideration of interference in thin coatings and scattering at textured interfaces with a mixed electronic-ionic drift-diffusion transport model that captures the peculiarities of the geometries and materials used in the tandem architecture.

X. Yang, Y. Lin, J. Liu, W. Liu, Q. Bi, X. Song, Jingxuan Kang,

F. Xu, L. Xu, M. N. Hedhili, D. Baran, X. Zhang, T. D. Anthopoulos, S. De Wolf

Adv. Mater. 2020, 2002608

https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202002608

The authors developed an efficient electron‐selective contact for for crystalline silicon (c‐Si) and organic photovoltaic devices. Titanium oxynitride (TiOxNy), is deposited by Atomic‐layer‐deposition and demonstrated to be highly conductive with a proper work function (4.3 eV) and a wide bandgap (3.4 eV). A state‐of‐the‐art PCE of 22.3% is achieved for a c‐Si solar cell featuring a full‐area dopant‐free electron‐selective contact. Simultaneously, conductive TiOxNy is proven to be an efficient electron‐transport layer for organic photovoltaic (OPV) devices. A remarkably high PCE of 17.02% is achieved for an OPV device.

Ardalan Armin, Nasim Zarrabi, Oskar J. Sandberg, Christina Kaiser, Stefan Zeiske, Wei Li, and Paul Meredith

Adv. Energy Mater. 2020, 2001828

https://onlinelibrary.wiley.com/doi/10.1002/aenm.202001828

Free carrier photogeneration in bulk‐heterojunction solar cells composed of blends of acceptor and donor organic semiconductors proceeds via intermolecular charge transfer (CT) states. The authors are showing that the Non-adiabatic Marcus theory has limitations when explaining the absorption and emission of these sub‐gap states. In particular the impact of simple low finesse cavity interference effects acting as an uneven spectral filter for emission and absorption.

G. Zhang, V. Coropceanu, C.J. Brabec, J.-L. Bredas, H.-L. Yip & Y. Cao

Nat. Comm. 11, 3943 (2020)

https://www.nature.com/articles/s41467-020-17867-1

Experimental and theoretical modeling to reveal the structure-property-performance relationships of this state-of-the-art OSC system. The distinctive π–π molecular packing of Y6 not only exists in molecular single crystals but also in thin films. This is critical in enabling highly efficient charge generation in OSC systems with negligible donor-acceptor energy offset.

Qin, C., Matsushima, T., Potscavage, W.J. et al.

Nat. Photonics 14, 70–75 (2020).

https://doi.org/10.1038/s41566-019-0545-9

Description:

Perovskite light-emitting diodes are promising for next-generation lighting and displays because of their high colour purity and performance1. Although the management of singlet and triplet excitons is fundamental to the design of efficient organic light-emitting diodes, the nature of how excitons affect performance is still not clear in perovskite2,3,4 and quasi-two-dimensional (2D) perovskite-based devices5,6,7,8,9. Here, we show that triplet excitons are key to efficient emission in green quasi-2D perovskite devices and that quenching of triplets by the organic cation is a major loss path.

Yongzhen Chen, Xianjie Liu, Slawomir Braun, Ying Wang and Mats Fahlmana

The article was first published on 22 Oct 2020

J. Mater. Chem. C, 2020, Advance Article

https://pubs.rsc.org/en/content/articlelanding/2020/tc/c9tc05128g

Description:

Electron transport materials (ETMs) are widely used as interlayers to lower the cathode electrode work function in organic solar cells and organic light-emitting diodes, for example. The usual interpretation for their operating principle is a chemical interaction between the ETM and the electrode, inducing partial or integer charge transfer or collectively an intrinsic dipole moment caused by preferential molecular orientation. Herein, we systematically explore the commonly used ETM bathophenanthroline (BPhen) deposited on a series of conducting substrates.

Ahmed H. Balawi Zhipeng Kan Julien Gorenflot Paola Guarracino Neha Chaturvedi Alberto Privitera Shengjian Liu Yajun Gao Lorenzo Franco Pierre Beaujuge Frédéric Laquai

Solar RRL. June 2020 2000181

https://onlinelibrary.wiley.com/doi/abs/10.1002/solr.202000181

Description:

Methodology to analyse losses in all-polymer solar cells by TRPL, TA and TDCF. The authors found d either non-geminate recombination or field-dependent charge splitting to limit the FF. IV simulations for different OPV blends using their photophysically determined recombination parameters and recombination model (not bimolecular).

Yuanbao Lin Yuliar Firdaus Mohamad Insan Nugraha Feng Liu Safakath Karuthedath Abdul‐Hamid Emwas Weimin Zhang Akmaral Seitkhan Marios Neophytou Hendrik Faber Emre Yengel Iain McCulloch Leonidas Tsetseris Frédéric Laquai Thomas D. Anthopoulos

Advanced Science.Vol. 7, 1903419 April 8 (2020)

https://onlinelibrary.wiley.com/doi/full/10.1002/advs.201903419

Description:

The authors investigate of the n-type dopant benzyl viologen which modifies the charge transport and microstructure of the blend. The versatility of the approach is tested for 5 different systems.

J. Lu, W. Feng, G. Mei, J. Sun, C. Yan, D. Zhang,

K. Lin, D. Wu, K. Wang, and Z. Wei

Adv. Sci. 2020, 2000689

https://onlinelibrary.wiley.com/doi/full/10.1002/advs.202000689

Description:

An ultrathin PEDOT:PSS hole transporter layer is prepared by a water stripping method. The PEDOT:PSS can enhance ηc and LEE simultaneously in Pero-LEDs thanks to the improved carrier mobility, more matched energy level alignment, and reduced photon loss. The EQEs of Pero-LEDs based on 3D, quasi-3D, and quasi-2D perovskites obtain enhancements of 42%, 87%, and 111%, and the corresponding maximum EQE reaches 17.6%, 15.0%, and 6.8%, respectively.

A.Seitkhan, M. Neophytou, R. K. Hallani, J.Troughton, N. Gasparini, H. Faber, E. Abou-Hamad, M.N. Hedhili, G. T. Harrison, D.Baran, L. Tsetseris, T. D. Anthopoulos and I. McCulloch

Adv. Funct. Mater. 2020, 2004273

https://onlinelibrary.wiley.com/doi/10.1002/adfm.202004273

Description:

A simple approach for improving the electron extraction of the PC60BM electron transport layer (ETL) is presented by sequentially depositing Al:ZnO (AZO) and triphenyl-phosphine oxide (TPPO) on top of it, in a p–i–n device configuration. The efficiency of the resulting CH3NH3PbI3-based solar cell is shown to improve from 14.6%, measured for the control PC60BM-only cell, to 17.9% for double-ETL (PC60BM/AZO) and 19.2% for triple-ETL (PC60BM/AZO/TPPO)-based devices, respectively.

M. Schmid, K. Harms et al.

ACS Appl. Mater. Interfaces (2020), 12, 46, 51709

https://dx.doi.org/10.1021/acsami.0c14613

The preferential orientation of organometallic iridium complexes is at the cutting edge of the research on OLEDs. The authors present a sky-blue phosphorescent dye that shows variable alignment depending on systematic modifications of the ligands bound to the central iridium atom. Their results indicate a potential strategy to actively control the orientation of iridium-based emitters for OLEDs. Paios was used to perform capacitance−voltage measurements which show that the HTL exhibits flat band conditions and hole injection at biases below the built-in voltage.

M. Diethelm, L. Penninck, M. Regnat, T. Offermans, B Zimmermann, C. Kirsch, R. Hiestand, S. Altazin, B. Ruhstaller

Solar Energy 209 (2020) 186

https://doi.org/10.1016/j.solener.2020.08.058

Description:

The authors investigate the potential of computationally efficient finite element simulation (FEM) of solar cells and modules by considering planar electrodes coupled by a local current–voltage coupling law. Sheet resistances are determined by fitting current simulation results of an OPV solar cell to electroluminescence imaging data. Moreover, a thermal model is introduced that accounts for Joule heating due to an electrothermal coupling.

J. Liu, W. Liu, E. Aydin, G. T. Harrison, F. H. Isikgor, X. Yang, A. S. Subbiah, S. De Wolf

ACS Appl. Mater. Interfaces 2020, 12, 21, 23874

https://pubs.acs.org/doi/10.1021/acsami.0c03660

Description:

The authors investigated spiro-OMeTAD, which is the most widely used HTL for n–i–p devices, and revealed improved power conversion efficiency (PCE) and stability in perovskite solar cells (PSCs). They also demonstrated the applicability of TPFB doping to other triphenylamine-based HTLs.

Dimitrios Kourkoulos, Christoph Patron, Thorsten Erich Umbach,

Anne Manuela Umbach, and Klaus Meerholz

Physica Status Solidi (a) May 2020, 1900593

https://doi.org/10.1002/pssa.201900593

Description:

Limited outcoupling efficiencies are still a big problem in organic light‐emitting devices (OLEDs). In this contribution, a simple and general approach for enhancing the outcoupling efficiency of OLEDs is presented: by using a three‐step process, including electrospray deposition of a sacrificial material (step i), thin metal‐layer deposition (step ii), and elution of the sacrificial material (step iii), scattering metal structures are fabricated that can be used in cavity OLEDs. The integration into green‐emitting vacuum‐processed OLEDs yields in increased luminous efficiency and external quantum efficiency (EQE) by 30% and 27%, respectively.

Xiao, X., Wang, K., Ye, T. et al.

Commun Mater 1, 81 (2020).

https://doi.org/10.1038/s43246-020-00084-0

A new strategy has been introduced to enhance hole injection in perovskite light-emitting diodes (LEDs) by introducing an electric dipole layer. The use of MoO3 as the electric dipole layer between PEDOT:PSS (hole injection layer) and PVK (hole transport layer) generates electric dipoles, which efficiently enhance hole injection and increase the recombination rate.

Theoretical analysis and capacitance-voltage analyses demonstrate efficient hole injection by introducing the electric dipole layer. The proposed electric dipole layer structure has led to a high current efficiency of 72.7 cd A−1, showing that electric dipole layers can significantly enhance the performance of perovskite LEDs.

Simulations

The electrical simulations were performed with Setfos, which solves the drift-diffusion equations for electron and holes, and considers exciton formation, mdiffusion, and decay in the framework of radiating dipoles inside amcavity including the Purcell effect.

Sandra Jenatsch, Simon Züfle, Balthasar Blülle, and Beat Ruhstaller

Journal of Applied Physics 127, 031102 (2020)

https://doi.org/10.1063/1.5132599

Generally, Organic Light-Emitting Diodes (OLEDs) are characterized in steady-state. Adding electro-optical measurements in frequency and time domain helps to analyze charge carrier and exciton dynamics, and provides deeper insights into the device physics. In their recent publication “Combining steady-state with frequency and time domain data to quantitatively analyze charge transport in organic light-emitting diodes” Dr. Sandra Jenatsch and colleagues present an overview of frequently used measurement techniques and analytical models for OLEDs. The main part of this tutorial explains how to systematically fit the measured OLED characteristics with microscopic device simulations based on a charge drift-diffusion and exciton migration model in 1D. Moreover, the authors analyze the correlation and sensitivity of the determined material parameters and use the obtained device model to understand the limitations of the specific OLED they considered.

Qiwei Xu, Lingju Meng, Kaustubh Sinha, Farsad I. Chowdhury, Jun Hu, Xihua Wang

ACS Photonics 2020, 7, 1297

https://pubs.acs.org/doi/abs/10.1021/acsphotonics.0c00363

Description:

PbS QDs photodetectors with short rise/fall times (0.33 μs), high sensitivity, and EQE exceeding 100% have been presented by the group of Prof. Xihua Wang. The charge mobility and the epsilon of the active layer were obtained by using photo-CELIV, dark-CELIV, and C-V measurements. The transit time is proportional to the thickness, while the capacitance and the RC time delay are inversely proportional.

Rebecca Momper, Heng Zhang, Shuai Chen, Henry Halim, Ewald Johannes, Stoyan Yordanov, Daniele Braga, Balthasar Blülle, David Doblas, Tobias Kraus, Mischa Bonn, Hai I. Wang, and Andreas Riedinger

Nano Letters (2020)

https://pubs.acs.org/doi/10.1021/acs.nanolett.9b05270

Description:

The authors discover that collective nanoplatelets orientation in monolayers can be controlled kinetically by exploiting the solvent evaporation rate in self-assembly at liquid interfaces. The ability to kinetically control the assembly of nanoplatelets into ordered monolayers with tunable optical and electronic properties paves the way for new applications in optoelectronic devices.

Jakub Jagielski, Simon F. Solari, Lucie Jordan, Declan Scullion, Balthasar Blülle, Yen-Ting Li, Frank Krumeich, Yu-Cheng Chiu, Beat Ruhstaller, Elton J. G. Santos and Chih-Jen Shih

Nature Communications 11, 387 (2020)

https://www.nature.com/articles/s41467-019-14084-3

Description:

The authors report decoupled multi-quantum-well superlattices comprised of colloidal quantum wells of lead halide perovskites, with unprecedentedly ultrathin quantum barriers that screen interlayer interactions within the range of 6.5 Å. Crystallographic and 2D k-space spectroscopic analysis reveals that the transition dipole moment orientation of bright excitons in the superlattices is predominantly in-plane and independent of the stacking layer and quantum barrier thickness, confirming interlayer decoupling.

Yuliar Firdaus, Qiao He, Yuanbao Lin, Ferry Anggoro Ardy Nugroho, Vincent M. Le Corre, Emre Yengel, Ahmed H. Balawi, Akmaral Seitkhan, Frédéric Laquai, Christoph Langhammer, Feng Liu, Martin Heeney and Thomas D. Anthopoulos

Journal of Materials Chemistry A 2020

https://doi.org/10.1039/C9TA11752K

Description:

The authors show a new wide bandgap acceptor which can be applied in tandem solar cells. The authors use Setfos to simulate the single and tandem device layer thicknesses and thus optimize efficiency. Furthermore, they thoroughly characterize the cells using the Paios platform in order to understand the different efficiency among different acceptors.

Yu Esaki, Masaki Tanaka, Toshinori Matsushima, Chihaya Adachi

Adv. Elec. Mat. 2100486, 25 June 2021

doi.org/10.1002/aelm.202100486

In this paper, the researchers analyzed the effect of substrate temperature on the orientation (PDM) of Alq3 and try to relate it to OLED performance. They observed a 40% increase in EQE with increasing temperature. Most stable OLEDs were found for room temperature processed devices.

Setfos was used to consider the different nk data of Alq3 and to simulate the change in outcoupling efficiency. With this simple simulation, they could explain 10% increase or the 40% experimental EQE enhancement.

Mohammad Alvar, Paul W. M. Blom & Gert-Jan A. H. Wetzelaer

ACS Appl. Mater. Interfaces 2020, 12, 21, 23874

https://www.nature.com/articles/s41467-020-17868-0

Description:

Researchers at the Max Planck Institute for Polymer Research developed a rigorous framework to extract the charge mobility from the SCLC-JV characteristics of pero-PVs. This work demonstrates also how to combine experiments and simulations to gain reliable insights into the transport mechanisms in a perovskite. PAIOS helped them performing scan-dependent electrical characterizations on their devices at different temperatures.