Review
Chemistry, Multidisciplinary
Junwei Shi, Chenyu Zhao, Jianyu Yuan
Summary: Inverted p-i-n lead halide perovskite solar cells (PSCs) have great potential for commercialization and compatibility with silicon (Si) bottom devices. However, their fill factor (FF) currently underperforms compared to other parameters. This review article summarizes recent advancements in improving FF in inverted PSCs through interfacial optimization, precursor engineering, and fabrication techniques. Insufficient carrier extraction and transport efficiency are identified as the main factors hindering FF, and strategies for minimizing series resistance are discussed. Continued efforts to improve FF in high-performance inverted devices may lead to commercial applications of PSCs in the future.
Article
Chemistry, Multidisciplinary
Lorenzo Di Mario, David Garcia Romero, Han Wang, Eelco K. Tekelenburg, Sander Meems, Teodor Zaharia, Giuseppe Portale, Maria A. Loi
Summary: Transport layers play a crucial role in thin-film solar cells, impacting both efficiency and stability. In this study, highly efficient organic solar cells were achieved using ALD-deposited SnO2 as the electron transport layer. The ALD-SnO2-based devices outperformed those with solution-casted SnO2 nanoparticles and sol-gel ZnO, exhibiting higher efficiency and stability. This improvement is attributed to reduced charge carrier recombination at the ALD-SnO2/active layer interface.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Min Ju Jeong, Soo Woong Jeon, Sung Yong Kim, Jun Hong Noh
Summary: To improve the air stability and efficiency of CsPbI2Br-based perovskite solar cells, researchers managed crystallization by incorporating sodium formate (NaFo) into the perovskite solution, resulting in increased grain size and reduced trap density. The NaFo-incorporated device exhibited improved air stability, retaining over 95% of its initial efficiency after 1000 hours under 10% relative humidity at room temperature without any encapsulation.
ADVANCED ENERGY MATERIALS
(2023)
Article
Energy & Fuels
Luca Serenelli, Luca Martini, Francesca Menchini, Massimo Izzi, Giampiero Cesare, Giuseppe Condorelli, Cosimo Gerardi, Delfina Munoz, Mario Tucci
Summary: Crystalline silicon-based heterojunction solar cells have become the preferred choice for manufacturing companies due to their low temperature processes and high efficiencies. However, the maximum efficiency is still limited by factors such as Fill Factor and base contact issues. Addressing hidden barriers at the base contact and recognizing barriers at the emitter side are crucial for improving cell efficiency.
PROGRESS IN PHOTOVOLTAICS
(2021)
Article
Energy & Fuels
Junwei Shi, Fangchao Li, Cheng Liu, Xufeng Ling, Xuliang Zhang, Yao Wang, Junjun Guo, Chenyu Zhao, Deng Wang, Youyong Li, Wanli Ma, Jianyu Yuan, Baomin Xu
Summary: Efficient inverted p-i-n architecture perovskite solar cells (PSCs) with high performance are achieved through sequential interfacial engineering of wet and dry metal-halide perovskite films assisted by organic molecules. This sequential treatment reduces surface trap states, non-radiative recombination, and carrier transport losses, leading to improved fill factor (FF), efficiency, and moisture stability.
Article
Chemistry, Physical
Peng Wang, Xinpeng Zhang, Zemin Zhang, Hao Ling, Lei Tao, Khumal Sohail, Xiangyu Li, Xue Fu, Xinwen Zhang, Ruixiao Wang, Yuxin Wang, Jingshan Luo, Min Jae Ko, Jiangzhao Chen, Yuelong Li
Summary: The negative pressure evaporation (NPE) method is used to quickly prepare tin dioxide (SnO2) electron transport layers (ETLs) at room temperature, which improves the surface morphology and conductivity compared to traditional thermal annealing. NPE-SnO2 enhances the fill factor and power conversion efficiency of perovskite solar cells (PSCs) and provides a universal technique for high-quality semiconductor film fabrication without thermal annealing.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Chemistry, Physical
Aaron Kramer, Waldemar Kaiser, Boya Zhang, Lakshmi N. S. Murthy, Alessio Gagliardi, Julia W. P. Hsu, William G. Vandenberghe
Summary: Organic solar cells using small molecule donors have lower fill factors compared to those using polymer donors. This is due to the limited collection region of charges in small molecule solar cells, while polymer solar cells can collect charges from a deeper volume. The fill factor of small molecule solar cells can be improved by adjusting the active layer morphology or reducing the energy offset between the donor and acceptor.
Article
Chemistry, Physical
Johan Lauwaert
Summary: In this article, a theoretical calculation is presented to analyze the voltage loss induced by an unfavorable direct tunneling interface between the window layer of a CIGS solar cell and the hole transport layer of a perovskite solar cell. It is found that a small interface band gap energy and a high surface recombination velocity can limit the losses caused by the recombination junction. Additionally, the increased doping in the ZnO:Al layer is detrimental to the fill factor of the tandem solar cell.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Energy & Fuels
Gaia M. N. Javier, Priya Dwivedi, Yoann Buratti, Ivan Perez-Wurfl, Thorsten Trupke, Ziv Hameiri
Summary: This study evaluates and enhances the accuracy of commonly used expressions for the fill factor (FF), and investigates parameters that can affect the accuracy of the revised expressions. The empirical coefficients of the commonly used analytical expressions are recalculated using a modified fitting approach. While the predictions of the revised expressions match the results of theoretical simulations, discrepancies are observed when compared to actual measurements. The study explores the different impacts of unaccounted factors in the expressions, and suggests adjusting the ideality factor or considering edge recombination to improve the accuracy of predictions. Additionally, the expressions may slightly overestimate the FF of cells with non-uniform implied open-circuit voltage distribution. The findings of this study can be helpful in developing techniques for extracting FF from luminescence images of industrial solar cells as electrical parameter extraction methods from such images continue to improve.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)
Article
Energy & Fuels
Chunfang Xing, Wenbo Gu, Kun Gao, Beibei Shao, Conghui Jiang, Guilin Bai, Dacheng Xu, Xinyu Wang, Kun Li, Zheheng Song, Zhaojun Su, Jie Mao, Xinyu Zhang, Peiting Zheng, Wei Zhang, Xiaohong Zhang, Yusheng Wang, Xinbo Yang, Baoquan Sun
Summary: In this study, thermally evaporated wide-bandgap strontium oxide (SrOx) was used as an electron-selective contact to improve the performance of crystalline silicon (c-Si) solar cells. The lower work function of SrOx achieved a downward band bending at the n-type c-Si/SrOx interface, enabling electron-selective transport. The thin SrOx films provided moderate surface passivation and low contact resistivity, leading to a champion power conversion efficiency of 20.0% on the n-type c-Si solar cell.
Article
Energy & Fuels
Chen Li, Fan Xu, Yujiao Li, Ning Li, Huanqin Yu, Beilei Yuanb, Zhaolai Chen, Liang Li, Bingqiang Cao
Summary: In this study, a strategy for preparing high-efficiency perovskite solar cells was reported, which involves growing highly-oriented perovskite films using a highly-purity MAPbI(3) crystal based film precursor solution to enhance light absorption ability and photocarriers transportation and extraction.
Article
Energy & Fuels
Salma Zouhair, Bin Luo, Dmitry Bogachuk, David Martineau, Lukas Wagner, Adil Chahboun, Stefan W. Glunz, Andreas Hinsch
Summary: This study found that high fill factors of up to 78.8% can be achieved through hole selective layer-free carbon-electrode perovskite solar cells. Non-radiative recombination contributes only 3% to the fill factor losses in optimized devices, while interface series resistance losses are identified as the main loss channel.
Article
Chemistry, Physical
Xianjin Wang, Chao Luo, Feng Gao, Changling Zhan, Yang Li, Qing Zhao
Summary: Unlike the upper interface, the substrate interface in n-i-p perovskite solar cells (PSCs) transports both carriers and photons. Managing this interface is crucial for manufacturing high-efficiency PSCs, but has been largely unexplored. In this study, micro-/nano-antireflection structures were constructed to reduce photon loss through substrate interface engineering. Energy level alignment at the substrate interface was also improved to enhance carrier extraction. This tailored substrate interface significantly improved the photovoltaic performance of PSCs, achieving a power conversion efficiency of up to 24.47%.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Chemistry, Physical
Julian Guerrero, Elisabeth Bajard, Nathanaelle Schneider, Fabienne Dumoulin, Daniel Lincot, Umit Isci, Marc Robert, Negar Naghavi
Summary: Using an electrochemical method, we developed transparent and conductive ZnO nanoporous layers that encapsulate molecular catalysts, serving as both a window layer for thin-film solar cells and a catalytic layer for solar-to-fuel conversion. We demonstrated the conversion of CO2 into CO with high selectivity and current densities using tetraammonium-substituted Co phthalocyanine encapsulated in the window layer of Cu(In,Ga)Se-2 solar cells, achieving a turnover number of above 100,000 and a turnover frequency of 10s(-1) after 3 hours of operation under 1 sun irradiation. This approach has the potential for adapting to various high-efficiency solar cells and facilitating the testing of different molecular catalysts for CO2 conversion into valuable fuels.
ACS ENERGY LETTERS
(2023)
Article
Chemistry, Physical
Jiafan Zhang, Linfeng Lu, Juan Zhang, Sha Li, Xiaoming Hua, Xiangrong Zhu, Yi-An Ding, Yinyue Lin, Shan -Ting Zhang, Dongdong Li
Summary: The application of zinc-doped indium oxide (IZO) thin films obtained by room-temperature sputtering in monolithic perovskite/silicon tandem solar cells is studied. IZO thin films with resistivity and electron mobility of 7.2 x 10-4 Omega cm and 40.03 cm2/Vs were obtained under 85W and implemented in monolithic perovskite/silicon tandem solar cells, achieving a PCE of 19.38%.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Anthony Donakowski, D. Westley Miller, Nicholas C. Anderson, Anthony Ruth, Erin M. Sanehira, Joseph J. Berry, Michael D. Irwin, Angus Rockett, K. Xerxes Steirer
Summary: Through time-resolved in situ X-ray photoelectron spectroscopy, rapid degradation mechanisms for cesium-stabilized formamidinium lead iodide perovskite materials used in state-of-the-art photovoltaics have been identified and suppressed. The fast degradation process is consistent with a 2D crystallization and growth mechanism fueled by excess halide salt, while a slower degradation pathway is found in more stoichiometric samples. Additionally, the decomposition rate varies significantly with the wavelength of light used for illumination.
ACS ENERGY LETTERS
(2021)
Article
Energy & Fuels
Laura T. Schelhas, Joseph J. Berry
Summary: Researchers have proposed a method to analyze field data to identify the changes in performance of metal halide perovskite solar cells over time in outdoor conditions. This will help bridge the gap between lab settings and real-world applications.
Article
Chemistry, Multidisciplinary
Fei Zhang, Haipeng Lu, Bryon W. Larson, Chuanxiao Xiao, Sean P. Dunfield, Obadiah G. Reid, Xihan Chen, Mengjin Yang, Joseph J. Berry, Matthew C. Beard, Kai Zhu
Summary: Surface modification with a new compound, Me-PDAI(2), on standard perovskite thin films can induce the formation of a thin perovskitoid surface layer, leading to improved efficiency and stability of the solar cells.
Article
Chemistry, Physical
Jin Hyuck Heo, Fei Zhang, Chuanxiao Xiao, Su Jeong Heo, Jin Kyoung Park, Joseph J. Berry, Kai Zhu, Sang Hyuk Im
Summary: In this study, inorganic CsPbI2Br-based perovskite thin films with a well-defined CsPbI3-xBrx composition gradient were fabricated using a scalable and orthogonal processable spray-coating approach. The graded structure broadened the absorption wavelength range, increased carrier lifetime, and improved charge separation and collection efficiency within a device stack. The power conversion efficiency reached 16.81% for a 0.096-cm(2) PSC, and a monolithically integrated perovskite sub-module achieved an efficiency of 13.82% with less than 9% degradation over 1,000 hours of continuous 1-sun light soaking.
Article
Chemistry, Physical
Narges Yaghoobi Nia, Mahmoud Zendehdel, Mojtaba Abdi-Jalebi, Luigi Angelo Castriotta, Felix U. Kosasih, Enrico Lamanna, Mohammad Mahdi Abolhasani, Zhaoxiang Zheng, Zahra Andaji-Garmaroudi, Kamal Asadi, Giorgio Divitini, Caterina Ducati, Richard H. Friend, Aldo Di Carlo
Summary: By varying the molecular weight of doped poly(triarylamine)(PTAA) HTL, the charge mobility inside the HTL and the charge transfer at the perovskite/HTL interface of PSCs were significantly improved in this study. Stable PSCs and perovskite solar modules with high efficiency were successfully demonstrated using a doping-MW strategy. These results pave the way for the industrialization of PSC-based photovoltaic technology.
Article
Energy & Fuels
Davide Regaldo, Aleksandra Bojar, Sean P. Dunfield, Pilar Lopez-Varo, Mathieu Fregnaux, Vincent Dufoulon, Shan-Ting Zhang, Jose Alvarez, Joseph J. Berry, Jean-Baptiste Puel, Philip Schulz, Jean-Paul Kleider
Summary: Lead halide perovskites are utilized in semiconductor devices as absorbers with low doping levels to achieve high surface photovoltage values. Drift-diffusion simulations show that under continuous illumination, intrinsic perovskite-SCTL structures can develop mV range surface photovoltages, while actual measurements confirm SPVs in the hundreds of mV. The compatibility between low doping and defect densities in the perovskite layer and high SPV values is analyzed using numerical modeling to understand the electronic processes contributing to long SPV persistence after the illumination is switched off.
PROGRESS IN PHOTOVOLTAICS
(2022)
Article
Chemistry, Physical
Moses Kodur, Zachary Dorfman, Ross A. Kerner, Justin H. Skaggs, Taewoo Kim, Sean P. Dunfield, Axel Palmstrom, Joseph J. Berry, David P. Fenning
Summary: Optimizing selective contact layers in photovoltaics is essential for high-performing stable devices. Using vacuum thermally evaporated tin oxide as a case study demonstrates the effectiveness of simple electrochemical tests in screening device-relevant contact layer properties, aiding in process development and quality control. Fast, reliable, scalable, and actionable probes of electronic properties become increasingly important as halide perovskite photovoltaics approach their theoretical limits and scale to large-area devices.
ACS ENERGY LETTERS
(2022)
Article
Chemistry, Physical
Laura E. Mundt, Fei Zhang, Axel F. Palmstrom, Junwei Xu, Robert Tirawat, Leah L. Kelly, Kevin H. Stone, Kai Zhu, Joseph J. Berry, Michael F. Toney, Laura T. Schelhas
Summary: This study demonstrates the impact of nanoscale compositional heterogeneity on the long-term stability of MHP solar cells using mixed A-site FA(0.83)Cs(0.17)PbI(3), and reveals that thermal annealing conditions during film processing can influence nan-scale compositional heterogeneity, with potential to improve device performance stability.
ACS ENERGY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Young-Hoon Kim, Ruyi Song, Ji Hao, Yaxin Zhai, Liang Yan, Taylor Moot, Axel F. Palmstrom, Roman Brunecky, Wei You, Joseph J. Berry, Jeffrey L. Blackburn, Matthew C. Beard, Volker Blum, Joseph M. Luther
Summary: This study investigates how chiral ligands attached to perovskite nanocrystal surfaces distort the perovskite lattice and demonstrates the resulting chiral electro-optical properties. The major finding is a centro-asymmetric distortion of the surface lattice, which is likely the cause of the chiral-optical properties. Spin-polarized transport through chiral nanocrystals amplifies the discrimination between left and right-handed circularly polarized light.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Physical
Samuel Berweger, Fei Zhang, Bryon W. Larson, Andrew J. Ferguson, Axel F. Palmstrom, Obadiah G. Reid, Thomas M. Wallis, Kai Zhu, Joseph J. Berry, Pavel Kabos, Sanjini U. Nanayakkara
Summary: The optoelectronic properties of lead halide perovskite thin films can be tuned through compositional variations and strain. However, the nanocrystalline structure complicates the understanding of the link between composition, processing conditions, and material properties. In this study, the local photoconductivity dynamics of perovskite thin films were investigated under different processing conditions and degradation using microwave near-field microscopy. The results showed that the annealing temperature during the processing affected the film morphology, stability, and spatial photoconductivity distribution. Spectral evidence of halide segregation-induced degradation was found in the mixed halide formulation, while an increase in carrier lifetime was observed in the FACs formulation annealed at 180 degrees C.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Editorial Material
Chemistry, Physical
E. Ashley Gaulding, Amy E. Louks, Mengjin Yang, Robert Tirawat, Mickey J. Wilson, Liam K. Shaw, Timothy J. Silverman, Joseph M. Luther, Axel F. Palmstrom, Joseph J. Berry, Matthew O. Reese
ACS ENERGY LETTERS
(2022)
Article
Chemistry, Physical
Ross A. Kerner, Kelly Schutt, Kai Zhu, Joseph J. Berry
Summary: Non-negligible impurities of acetate and nitrate have been found in commercially available PbI2 reagents, which can accelerate the degradation of mixed-cation halide perovskite inks. Therefore, better control of the purity of halide perovskites is necessary.
ACS ENERGY LETTERS
(2022)
Article
Chemistry, Physical
Ross A. Kerner, Earl D. Christensen, Steven P. Harvey, Jonah Messinger, Severin N. Habisreutinger, Fei Zhang, Giles E. Eperon, Laura T. Schelhas, Kai Zhu, Joseph J. Berry, David T. Moore
Summary: Using higher quality reagents to synthesize halide perovskite materials can improve their optoelectronic performance. In this study, we investigated the influence of different PbI2 reagent sources on device performance and identified acetate and potassium as key impurities affecting performance. A simple aqueous recrystallization method successfully reduced impurity concentration and improved device performance.
ACS APPLIED ENERGY MATERIALS
(2022)
Article
Energy & Fuels
Jackson W. Schall, Andrew Glaws, Nutifafa Y. Doumon, Timothy J. Silverman, Michael Owen-Bellini, Kent Terwilliger, Md Aslam Uddin, Prem Rana, Joseph J. Berry, Jinsong Huang, Laura T. Schelhas, Dana B. Kern
Summary: In this study, electroluminescence (EL) and thermal imaging were used to investigate the degradation of metal halide perovskite (MHP) photovoltaic (PV) mini-modules. Different spatial patterns were observed in the EL images depending on the external stress conditions. Dark speckle features dominated after UV stress, while lateral intensity gradients were prominent after thermal cycling stress. Multimodal electro-optical imaging, including EL, photoluminescence and dark lock-in thermography, provided a deeper understanding of the degradation modes. UV exposure and thermal cycling stress testing alone could not replicate the same degradation signatures observed after outdoor deployment, indicating the occurrence of multiple degradation modes. The spatial characterization of degradation modes provides a foundation for developing targeted accelerated stress testing procedures by comparing with outdoor aging.
Article
Multidisciplinary Sciences
Qi Jiang, Robert Tirawat, Ross A. Kerner, E. Ashley Gaulding, Yeming Xian, Xiaoming Wang, Jimmy M. Newkirk, Yanfa Yan, Joseph J. Berry, Kai Zhu
Summary: Metal halide perovskite solar cells (PSCs) show great potential as a low-cost thin-film photovoltaic technology. To ensure their commercialization, it is important to understand their reliability under real-world outdoor conditions. This study demonstrates that indoor accelerated stability tests can predict the performance of PSCs in outdoor environments. The degradation rates under illumination and elevated temperatures are found to be the most informative for assessing device reliability. The study also identifies the interface between indium tin oxide/self-assembled monolayer-based hole transport layer and perovskite layer as a key factor affecting device stability.
