Precisely Controlling the Grain Sizes with an Ammonium Hypophosphite Additive for High‐Performance Perovskite Solar Cells |
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| Authors: | Weidong Xu Gang Lei Chen Tao Jiandong Zhang Xiaoke Liu Xiang Xu Wen‐Yong Lai Feng Gao Wei Huang |
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| Affiliation: | 1. Key Laboratory for Organic Electronics and Information Displays (KLOEID) & Institute of Advanced Materials (IAM), National Jiangsu Syngerstic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts and Telecommunications, Nanjing, China;2. Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, China;3. Department of Physics, Chemistry and Biology (IFM), Link?ping University, Link?ping, Sweden;4. Key Laboratory of Artificial Micro‐ and Nano‐structures of Ministry of Education of China, School of Physics and Technology, Wuhan University, Wuhan, P. R. China;5. Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), Xi'an, China |
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| Abstract: | A facile approach to precisely control the perovskite grain sizes is proposed and demonstrated for high‐performance photovoltaic (PV) solar cells. With the introduction of various amounts of NH4H2PO2 (AHP) additives into the PbI2/CH3NH3I precursors, the grain scale of CH3NH3PbI3 films can be finely turned from hundreds of nanometer to micrometer scale, allowing evaluating the effects of crystalline grain boundary on trap densities, charge recombination, and PV device performance. The X‐ray diffraction and X‐ray photoelectron spectroscopy measurements indicate that the formation of intermediates plays a key role in assisting the perovskite crystal growth. The optimized devices show much larger open‐circuit voltages (VOC) up to 1.10 ± 0.02 V and significantly enhance power conversion efficiencies (PCEs) of 16.5 ± 0.7%, as compared to the control devices with PCE of 9.4 ± 1.0% and VOC of 1.00 ± 0.03 V. Further investigations confirm that the boosted PV performance origins from the decreased defect densities due to enlarged grain sizes. It is also demonstrated that the approach is general and applicable to other perovskite systems, e.g., HC(NH2)2PbI3. The results suggest the promising application of AHP in achieving high‐performance perovskite PV devices, and shed light on understanding the grain boundary effects on perovskite optoelectronics. |
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| Keywords: | ammonium hypophosphite additives crystal growth crystalline grain boundary perovskite perovskite solar cells |
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