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3,642 results on '"Grätzel, Michael"'

1. All-perovskite tandem solar cells achieving >29% efficiency with improved (100) orientation in wide-bandgap perovskites

Author

Liu, Zhou, Lin, Renxing, Wei, Mingyang, Yin, Mengran, Wu, Pu, Li, Manya, Li, Ludong, Wang, Yurui, Chen, Gang, Carnevali, Virginia, Agosta, Lorenzo, Slama, Vladislav, Lempesis, Nikolaos, Wang, Zhichao, Wang, Meiyu, Deng, Yu, Luo, Haowen, Gao, Han, Rothlisberger, Ursula, Zakeeruddin, Shaik M., Luo, Xin, Liu, Ye, Grätzel, Michael, and Tan, Hairen

Published
2025
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2. Suppressing wide-angle light loss and non-radiative recombination for efficient perovskite solar cells

Author

Ge, Yansong, Zheng, Likai, Wang, Haibing, Gao, Jing, Yao, Fang, Wang, Chen, Li, Guang, Guan, Hongling, Wang, Shuxin, Cui, Hongsen, Ye, Feihong, Shao, Wenlong, Zheng, Zhimiao, Yu, Zixi, Wang, Jiahao, Xu, Zuxiong, Dai, Chenjie, Ma, Yihan, Yang, Yi, Guan, Zhiqiang, Liu, Yong, Wang, Jianbo, Lin, Qianqian, Li, Zhongyang, Li, Xiong, Ke, Weijun, Grätzel, Michael, and Fang, Guojia

Published
2025
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6. High carrier mobility along the [111] orientation in Cu2O photoelectrodes

Author

Pan, Linfeng, Dai, Linjie, Burton, Oliver J., Chen, Lu, Andrei, Virgil, Zhang, Youcheng, Ren, Dan, Cheng, Jinshui, Wu, Linxiao, Frohna, Kyle, Abfalterer, Anna, Yang, Terry Chien-Jen, Niu, Wenzhe, Xia, Meng, Hofmann, Stephan, Dyson, Paul J., Reisner, Erwin, Sirringhaus, Henning, Luo, Jingshan, Hagfeldt, Anders, Grätzel, Michael, and Stranks, Samuel D.

Published
2024
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7. Enabling full-scale grain boundary mitigation in polycrystalline perovskite solids

Author

Zhao, Lichen, Tang, Pengyi, Luo, Deying, Dar, M Ibrahim, Eickemeyer, Felix T, Arora, Neha, Hu, Qin, Luo, Jingshan, Liu, Yuhang, Zakeeruddin, Shaik Mohammed, Hagfeldt, Anders, Arbiol, Jordi, Huang, Wei, Gong, Qihuang, Russell, Thomas P, Friend, Richard H, Grätzel, Michael, and Zhu, Rui

Subjects
Macromolecular and Materials Chemistry, Chemical Sciences, Physical Chemistry, Engineering, Materials Engineering
Abstract

There exists a considerable density of interaggregate grain boundaries (GBs) and intra-aggregate GBs in polycrystalline perovskites. Mitigation of intra-aggregate GBs is equally notable to that of interaggregate GBs as intra-aggregate GBs can also cause detrimental effects on the photovoltaic performances of perovskite solar cells (PSCs). Here, we demonstrate full-scale GB mitigation ranging from nanoscale intra-aggregate to submicron-scale interaggregate GBs, by modulating the crystallization kinetics using a judiciously designed brominated arylamine trimer. The optimized GB-mitigated perovskite films exhibit reduced nonradiative recombination, and their corresponding mesostructured PSCs show substantially enhanced device efficiency and long-term stability under illumination, humidity, or heat stress. The versatility of our strategy is also verified upon applying it to different categories of PSCs. Our discovery not only specifies a rarely addressed perspective concerning fundamental studies of perovskites at nanoscale but also opens a route to obtain high-quality solution-processed polycrystalline perovskites for high-performance optoelectronic devices.

Published
2022

8. Low-loss contacts on textured substrates for inverted perovskite solar cells

Author

Park, So Min, Wei, Mingyang, Lempesis, Nikolaos, Yu, Wenjin, Hossain, Tareq, Agosta, Lorenzo, Carnevali, Virginia, Atapattu, Harindi R., Serles, Peter, Eickemeyer, Felix T., Shin, Heejong, Vafaie, Maral, Choi, Deokjae, Darabi, Kasra, Jung, Eui Dae, Yang, Yi, Kim, Da Bin, Zakeeruddin, Shaik M., Chen, Bin, Amassian, Aram, Filleter, Tobin, Kanatzidis, Mercouri G., Graham, Kenneth R., Xiao, Lixin, Rothlisberger, Ursula, Grätzel, Michael, and Sargent, Edward H.

Published
2023
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13. Publisher Correction: High carrier mobility along the [111] orientation in Cu2O photoelectrodes

Author

Pan, Linfeng, Dai, Linjie, Burton, Oliver J., Chen, Lu, Andrei, Virgil, Zhang, Youcheng, Ren, Dan, Cheng, Jinshui, Wu, Linxiao, Frohna, Kyle, Abfalterer, Anna, Yang, Terry Chien-Jen, Niu, Wenzhe, Xia, Meng, Hofmann, Stephan, Dyson, Paul J., Reisner, Erwin, Sirringhaus, Henning, Luo, Jingshan, Hagfeldt, Anders, Grätzel, Michael, and Stranks, Samuel D.

Published
2024
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14. Suppressed phase segregation for triple-junction perovskite solar cells

Author

Wang, Zaiwei, Zeng, Lewei, Zhu, Tong, Chen, Hao, Chen, Bin, Kubicki, Dominik J., Balvanz, Adam, Li, Chongwen, Maxwell, Aidan, Ugur, Esma, dos Reis, Roberto, Cheng, Matthew, Yang, Guang, Subedi, Biwas, Luo, Deying, Hu, Juntao, Wang, Junke, Teale, Sam, Mahesh, Suhas, Wang, Sasa, Hu, Shuangyan, Jung, Eui Dae, Wei, Mingyang, Park, So Min, Grater, Luke, Aydin, Erkan, Song, Zhaoning, Podraza, Nikolas J., Lu, Zheng-Hong, Huang, Jinsong, Dravid, Vinayak P., De Wolf, Stefaan, Yan, Yanfa, Grätzel, Michael, Kanatzidis, Merx G., and Sargent, Edward H.

Published
2023
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26. Author Correction: A universal co-solvent dilution strategy enables facile and cost-effective fabrication of perovskite photovoltaics

Author

Zhang, Hong, Darabi, Kasra, Nia, Narges Yaghoobi, Krishna, Anurag, Ahlawat, Paramvir, Guo, Boyu, Almalki, Masaud Hassan S., Su, Tzu-Sen, Ren, Dan, Bolnykh, Viacheslav, Castriotta, Luigi Angelo, Zendehdel, Mahmoud, Pan, Linfeng, Alonso, Sandy Sanchez, Li, Ruipeng, Zakeeruddin, Shaik M., Hagfeldt, Anders, Rothlisberger, Ursula, Di Carlo, Aldo, Amassian, Aram, and Grätzel, Michael

Published
2022
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27. A universal co-solvent dilution strategy enables facile and cost-effective fabrication of perovskite photovoltaics

Author

Zhang, Hong, Darabi, Kasra, Nia, Narges Yaghoobi, Krishna, Anurag, Ahlawat, Paramvir, Guo, Boyu, Almalki, Masaud Hassan S., Su, Tzu-Sen, Ren, Dan, Bolnykh, Viacheslav, Castriotta, Luigi Angelo, Zendehdel, Mahmoud, Pan, Linfeng, Alonso, Sandy Sanchez, Li, Ruipeng, Zakeeruddin, Shaik M., Hagfeldt, Anders, Rothlisberger, Ursula, Di Carlo, Aldo, Amassian, Aram, and Grätzel, Michael

Published
2022
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28. Computational Characterization of the Dependence of Halide Perovskite Effective Masses on Chemical Composition and Structure

Author

Ashari-Astani, Negar, Meloni, Simone, Salavati, Amir Hesam, Palermo, Giulia, Grätzel, Michael, and Rothlisberger, Ursula

Subjects
Chemical Sciences, Engineering, Technology, Physical Chemistry
Abstract

Effective masses are calculated for a large variety of perovskites of the form ABX3 differing in chemical composition (A= Na, Li, Cs; B = Pb, Sn; X= Cl, Br, I) and crystal structure. In addition, the effects of some defects and dopants are assessed. We show that the effective masses are highly correlated with the energies of the valence-band maximum, conduction-band minimum, and band gap. Using the k·p theory for the bottom of the conduction band and a tight-binding model for the top of the valence band, this trend can be rationalized in terms of the orbital overlap between halide and metal (B cation). Most of the compounds studied in this work are good charge-carrier transporters, where the effective masses of the Pb compounds (0 < mh∗ < me∗ < 1) are systematically larger than those of the Sn-based compounds (0 < mh∗ ≈ me∗ < 0.5). The effective masses show anisotropies depending on the crystal symmetry of the perovskite, whether orthorhombic, tetragonal, or cubic, with the highest anisotropy for the tetragonal phase (ca. 40%). In general, the effective masses of the perovskites remain low for intrinsic or extrinsic defects, apart from some notable exceptions. Whereas some dopants, such as Zn(II), flatten the conduction-band edges (me∗ = 1.7m0) and introduce deep defect states, vacancies, more specifically Pb2+ vacancies, make the valence-band edge more shallow (mh∗ = 0.9m0). From a device-performance point of view, introducing modifications that increase the orbital overlap [e.g., more cubic structures, larger halides, smaller (larger) monovalent cations in cubic (tetragonal/orthorhombic) structures] decreases the band gap and, with it, effective masses of the charge carriers.

Published
2017

29. In situ dynamic observations of perovskite crystallisation and microstructure evolution intermediated from [PbI6]4- cage nanoparticles.

Author

Hu, Qin, Zhao, Lichen, Wu, Jiang, Gao, Ke, Luo, Deying, Jiang, Yufeng, Zhang, Ziyi, Zhu, Chenhui, Schaible, Eric, Hexemer, Alexander, Wang, Cheng, Liu, Yi, Zhang, Wei, Grätzel, Michael, Liu, Feng, Russell, Thomas P, Zhu, Rui, and Gong, Qihuang

Abstract

Hybrid lead halide perovskites have emerged as high-performance photovoltaic materials with their extraordinary optoelectronic properties. In particular, the remarkable device efficiency is strongly influenced by the perovskite crystallinity and the film morphology. Here, we investigate the perovskites crystallisation kinetics and growth mechanism in real time from liquid precursor continually to the final uniform film. We utilize some advanced in situ characterisation techniques including synchrotron-based grazing incident X-ray diffraction to observe crystal structure and chemical transition of perovskites. The nano-assemble model from perovskite intermediated [PbI6]4- cage nanoparticles to bulk polycrystals is proposed to understand perovskites formation at a molecular- or nano-level. A crystallisation-depletion mechanism is developed to elucidate the periodic crystallisation and the kinetically trapped morphology at a mesoscopic level. Based on these in situ dynamics studies, the whole process of the perovskites formation and transformation from the molecular to the microstructure over relevant temperature and time scales is successfully demonstrated.

Published
2017

31. Investigation of the Directional Characteristics of the Emitted Airborne Sound by Friction Stir Welding for Online Process Monitoring

Author

Grätzel, Michael, primary, Other, Sven, additional, Stoll, Benedict, additional, Rohe, Maximilian, additional, Hasieber, Michael, additional, Löhn, Torsten, additional, Hildebrand, Jörg, additional, Bergmann, Jean Pierre, additional, Kátai, András, additional, Breitbarth, Kati, additional, and Bös, Joachim, additional

Published
2022
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32. Triarylamine Trisamide Interfacial Modulation for Perovskite Photovoltaics.

Author

Almalki, Masaud, AlSabeh, Ghewa, Ruiz‐Preciado, Marco A., Zhang, Hong, Galerne, Melodie, Moulin, Emilie, Eickemeyer, Felix Thomas, Zakeeruddin, Shaik M., Milić, Jovana V., Giuseppone, Nicolas, and Grätzel, Michael

Subjects
SOLAR cells, PHOTOVOLTAIC power generation, PEROVSKITE
Abstract

Hybrid perovskites stand out as one of the leading materials in the new generation of photovoltaics. Their stability under operating conditions, however, remains an ongoing challenge. In particular, aging at the interface with the charge transport materials contributes to the degradation during operation. To address this, functionalized triarylamine‐based modulators are employed, which are known to form hole‐transporting supramolecular stacks, at the interface between the perovskite active layer and the hole‐transporting material in conventional perovskite solar cells. As a result, the improvements of the operational stabilities are demonstrated without compromising device performances, providing a promising strategy for advancing photovoltaics. [ABSTRACT FROM AUTHOR]

Published
2024
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33. Failure mechanisms of Friction stir welding tools related to process control and tool geometry.

Author

Hasieber, Michael, Rudel, Paul, Sennewald, Martin, Löhn, Torsten, Grätzel, Michael, and Bergmann, Jean Pierre

Abstract

Friction stir welding (FSW) is subjected to process-specific challenges including comparatively high process forces and tool wear resulting from thermomechanical stresses. As a result, the acting loads and the geometric-related tool wear can cause tool failure. The tool (shoulder) design, whether it is concave or flat, with or without geometrical elements, is mainly responsible for the related failure mechanism and tool life. Therefore, this study systematically analyzes the failure mechanisms as a function of the process temperature, during FSW of AA-6060 T66 using tools made of H13 tool steel, with different shoulder designs, namely a concave contour and a scroll contour. The mechanism responsible for tool failure was induced by repeated welding at rotational speeds of 4000 rpm and 2000 rpm, at process temperatures within the range of the secondary hardness maximum (552 °C and 555 °C) and below the temperature of the secondary hardness maximum (488 °C and 499 °C). The experimental investigation showed that reducing the rotational speed of the scrolled shoulder from 4000 rpm to 2000 rpm resulted in less wear and therefore an increase in tool life from 474 m to up to 1400 m. In this context, it has also been shown that the shoulder geometry affects the mechanism relevant to failure due to the free length of the probe. [ABSTRACT FROM AUTHOR]

Published
2024
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34. Advanced High‐Throughput Rational Design of Porphyrin‐Sensitized Solar Cells Using Interpretable Machine Learning.

Author

Liao, Jian‐Ming, Chen, Yu‐Hsuan, Lee, Hsuan‐Wei, Guo, Bo‐Cheng, Su, Po‐Cheng, Wang, Lun‐Hong, Reddy, Nagannagari Masi, Yella, Aswani, Zhang, Zhao‐Jie, Chang, Chuan‐Yung, Chen, Chia‐Yuan, Zakeeruddin, Shaik M, Tsai, Hui‐Hsu Gavin, Yeh, Chen‐Yu, and Grätzel, Michael

Subjects
SOLAR cell design, MACHINE learning, PHOTOVOLTAIC cells, SOLAR cells, PREDICTION models, ZINC porphyrins
Abstract

Accurately predicting the power conversion efficiency (PCE) in dye‐sensitized solar cells (DSSCs) represents a crucial challenge, one that is pivotal for the high throughput rational design and screening of promising dye sensitizers. This study presents precise, predictive, and interpretable machine learning (ML) models specifically designed for Zn‐porphyrin‐sensitized solar cells. The model leverages theoretically computable, effective, and reusable molecular descriptors (MDs) to address this challenge. The models achieve excellent performance on a "blind test" of 17 newly designed cells, with a mean absolute error (MAE) of 1.02%. Notably, 10 dyes are predicted within a 1% error margin. These results validate the ML models and their importance in exploring uncharted chemical spaces of Zn‐porphyrins. SHAP analysis identifies crucial MDs that align well with experimental observations, providing valuable chemical guidelines for the rational design of dyes in DSSCs. These predictive ML models enable efficient in silico screening, significantly reducing analysis time for photovoltaic cells. Promising Zn‐porphyrin‐based dyes with exceptional PCE are identified, facilitating high‐throughput virtual screening. The prediction tool is publicly accessible at https://ai‐meta.chem.ncu.edu.tw/dsc‐meta. [ABSTRACT FROM AUTHOR]

Published
2024
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35. Tailored Supramolecular Interactions in Host–Guest Complexation for Efficient and Stable Perovskite Solar Cells and Modules.

Author

Yang, Guangyue, Liu, Xin, Wang, Linqin, Dong, Kaiwen, Zhang, Bingqian, Jiang, Xiaoqing, Yin, Yanfeng, Wang, Minhuan, Niu, Wenzhe, Zheng, Likai, Yu, Shitao, Liu, Shiwei, Zakeeruddin, Shaik M., Guo, Xin, Pang, Shuping, Sun, Licheng, Grätzel, Michael, and Wei, Mingyang

Subjects
SOLAR cells, DIPOLE moments, SURFACE defects, PEROVSKITE, PASSIVATION
Abstract

Host‐guest complexation offers a promising approach for mitigating surface defects in perovskite solar cells (PSCs). Crown ethers are the most widely used macrocyclic hosts for complexing perovskite surfaces, yet their supramolecular interactions and functional implications require further understanding. Here we show that the dipole moment of crown ethers serves as an indicator of supramolecular interactions with both perovskites and precursor salts. A larger dipole moment, achieved through the substitution of heteroatoms, correlates with enhanced coordination with lead cations. Perovskite films incorporating aza‐crown ethers as additives exhibited improved morphology, reduced defect densities, and better energy‐level alignment compared to those using native crown ethers. We report power‐conversion efficiencies (PCEs) exceeding 25 % for PSCs, which show enhanced long‐term stability, and a record PCE of 21.5 % for host–guest complexation‐based perovskite solar modules with an active area of 14.0 cm2. [ABSTRACT FROM AUTHOR]

Published
2024
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38. Methylammonium Nitrate-Mediated Crystal Growth and Defect Passivation in Lead Halide Perovskite Solar Cells

Author

Kim, Sun-Ju, primary, Cho, In Hwa, additional, Nguyen, Thanh-Danh, additional, Hong, Yun-Kyeong, additional, Kim, Yeonju, additional, Yum, Jun-Ho, additional, Sivula, Kevin, additional, Kang, Joonhee, additional, Kim, Hui-Seon, additional, Zakeeruddin, Shaik M., additional, Grätzel, Michael, additional, Kim, Hyo Jung, additional, and Seo, Ji-Youn, additional

Published
2024
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40. Pseudo-halide anion engineering for α-FAPbI3 perovskite solar cells

Author

Jeong, Jaeki, Kim, Minjin, Seo, Jongdeuk, Lu, Haizhou, Ahlawat, Paramvir, Mishra, Aditya, Yang, Yingguo, Hope, Michael A., Eickemeyer, Felix T., Kim, Maengsuk, Yoon, Yung Jin, Choi, In Woo, Darwich, Barbara Primera, Choi, Seung Ju, Jo, Yimhyun, Lee, Jun Hee, Walker, Bright, Zakeeruddin, Shaik M., Emsley, Lyndon, Rothlisberger, Ursula, Hagfeldt, Anders, Kim, Dong Suk, Grätzel, Michael, and Kim, Jin Young

Published
2021
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42. High Solar Flux Concentration Water Splitting with Hematite (α‐Fe2O3) Photoanodes

Author

Segev, Gideon, Dotan, Hen, Malviya, Kirtiman Deo, Kay, Asaf, Mayer, Matthew T, Grätzel, Michael, and Rothschild, Avner

Subjects
Macromolecular and Materials Chemistry, Materials Engineering, Interdisciplinary Engineering
Abstract

The water splitting performance of hematite photoanodes is explored under a wide range of light intensities. The photocurrent scales linearly and the photovoltage scales logarithmically with the intensity, showing steeper rate than in photovoltaics, probably due to the enhanced ratio between charge transfer and recombination at high intensities. Hence, light concentration serves as another handle to enhance the efficiency of hematite photoanodes.

Published
2016

43. Combined vacuum evaporation and solution process for high-efficiency large-area perovskite solar cells with exceptional reproducibility

Author

Tan, Liguo, Zhou, Junjie, Zhao, Xing, Wang, Siyang, Li, Minghao, Jiang, Chaofan, Li, Hang, Zhang, Yu, Ye, Yiran, Tress, Wolfgang, Ding, Liming, Grätzel, Michael, Yi, Chenyi, Tan, Liguo, Zhou, Junjie, Zhao, Xing, Wang, Siyang, Li, Minghao, Jiang, Chaofan, Li, Hang, Zhang, Yu, Ye, Yiran, Tress, Wolfgang, Ding, Liming, Grätzel, Michael, and Yi, Chenyi

Abstract

Organic-inorganic hybrid perovskites exhibit outstanding performances in perovskite solar cells (PSCs). However, the complex solution chemistry of perovskites precursors renders it difficult to prepare large-area devices in a reproducible way, which is a prerequisite for the technology to make an impact beyond lab scale. Vacuum processing, instead, is an established technology for large-scale coating of thin films. However, with respect to the hybrid perovskites it is highly challenging due to the high vapor pressure of the organic ammonium halide. In this work, vacuum evaporation of lead iodide and solution processing of organic ammonium halide is combined to produce large-area homogeneous perovskite films with large grains in a highly reproducible way. The resulting PSCs achieve a power conversion efficiency (PCE) of 24.3% (certified 23.9%) on small area (0.10 cm2 ), 24.0% (certified 23.7%) on large area (1 cm2 ) and 20.0% for minimodule (16 cm2 ), and maintain 90% of its initial efficiency after 1000 h 1-sun operation. The vacuum evaporation prevents advert environmental effects on lead halide formation and guarantees a reproducible fabrication of high-quality large-area perovskite films, which opens a promising way for large-scale fabrication of perovskite optoelectronics.

Published
2024

45. Spatial Conformation Engineering of Aromatic Ketones for Highly Efficient and Stable Perovskite Solar Cells

Author

Jiang, Xiaoqing, Zhu, Lina, Zhang, Bingqian, Zheng, Likai, Wang, Linqin, Li, Pingping, Wang, Minhuan, Yang, Guangyue, Dong, Kaiwen, Li, Suying, Liu, Shiwei, Yin, Yanfeng, Wang, Haiyuan, Zakeeruddin, Shaik. M., Pang, Shuping, Sun, Licheng, Grätzel, Michael, and Guo, Xin

Abstract

Carbonyl-containing materials employed in state-of-the-art hybrid lead halide perovskite solar cells (PSCs) exhibit a strong structure-dependent electron donor effect that predominates in defect passivation. However, the impact of the molecular spatial conformation on the efficacy of carbonyl-containing passivators remains ambiguous, hindering the advancement of molecular design for passivating materials. Herein, we show that altering the spatial torsion angle of aromatic ketones from twisted to planar configurations, as seen in benzophenone (BP, 27.2°), anthrone (AR, 15.3°), and 9-fluorenone (FO, 0°), leads to a notable increment of the electron cloud density around the carbonyl group, thus improving the passivation ability for lead-based defects. Consequently, the PSC performance also relies on the torsion angle of the aromatic ketones, with the coplanar FO-based PSC achieving a highest power conversion efficiency (PCE) of 25.13% and retaining 92% of its initial efficiency after 1000 h of operation at the maximum power point under continuous 1-sun illumination (ISOS-L-1I). Moreover, a perovskite mini-module (14.0 cm2) containing FO exhibits a PCE of 20.19%. Our findings highlight the influence of molecular conformation on the passivation effect of the carbonyl group, offering deeper insight into the design and development of aromatic ketones as passivators for highly efficient and stable PSCs.

Published
2024
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48. Multimodal host–guest complexation for efficient and stable perovskite photovoltaics

Author

Zhang, Hong, Eickemeyer, Felix Thomas, Zhou, Zhiwen, Mladenović, Marko, Jahanbakhshi, Farzaneh, Merten, Lena, Hinderhofer, Alexander, Hope, Michael A., Ouellette, Olivier, Mishra, Aditya, Ahlawat, Paramvir, Ren, Dan, Su, Tzu-Sen, Krishna, Anurag, Wang, Zaiwei, Dong, Zhaowen, Guo, Jinming, Zakeeruddin, Shaik M., Schreiber, Frank, Hagfeldt, Anders, Emsley, Lyndon, Rothlisberger, Ursula, Milić, Jovana V., and Grätzel, Michael

Published
2021
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