Chemical Reduction of Iodine Impurities and Defects with Potassium Formate for Efficient and Stable Perovskite Solar Cells |
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Authors: | Derun Sun You Gao Hasan Raza Sanwan Liu Fumeng Ren Xiaodong Hu Haixin Wang Xin Meng Jianan Wang Rui Chen Huande Sun Jizhou He Jing Zhou Yongyan Pan Zhenxing Sun Wei Chen Zonghao Liu |
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Affiliation: | 1. Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074 China;2. Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074 China
Optics Valley Laboratory, Hubei, 430074 China |
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Abstract: | The performance of perovskite solar cells (PSCs) is negatively affected by iodine (I2) impurities generated from the oxidation of iodide ions in the perovskite precursor powder, solution, and perovskite films. In this study, the use of potassium formate (HCOOK) as a reductant to minimize the presence of detrimental I2 impurities is presented. It is demonstrated that HCOOK can effectively reduce I2 back to I− in the precursor solution as well as in the devices under external conditions. Furthermore, the introduced formate anion (HCOO−) and alkali metal cation (K+) can reduce the defect density within the perovskite film by modulating perovskite growth and passivating electronic defects, significantly prolonging the carrier lifetime and reducing the J–V hysteresis. Consequently, the maximum efficiency of the HCOOK-doped planar n–i–p PSCs reaches 23.8%. After 1000 h of operation at maximum power point tracking under continuous 1 sun illumination, the corresponding encapsulated devices retain 94% of their initial efficiency. |
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Keywords: | chemical reduction defect passivation high performance perovskite solar cells potassium formate |
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