Multifunctional Organic Potassium Salt Additives as the Efficient Defect Passivator for High‐Efficiency and Stable Perovskite Solar Cells

• Published in: Advanced functional materials Vol. 33; no. 25
• Main Authors: Kong, Yingjie, Shen, Wenjian, Cai, Haoyu, Dong, Wei, Bai, Cong, Zhao, Juan, Huang, Fuzhi, Cheng, Yi‐Bing, Zhong, Jie
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.06.2023
• Subjects: additive engineering; Additives; Control equipment; Crystal defects; defect passivations; Efficiency; Energy conversion efficiency; Grain size; Hydrogen bonds; Materials science; organic potassium salts; perovskite solar cells; Perovskites; Photovoltaic cells; Potassium; Potassium salts; Solar cells; Stability
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202300932

Despite the rapid developments are achieved for perovskite solar cells (PSCs), the existence of various defects in the devices still limits the further enhancement of the power conversion efficiency (PCE) and the long‐term stability of devices. Herein, the efficient organic potassium salt (OPS) of para‐halogenated phenyl trifluoroborates is presented as the precursor additives to improve the performance of PSCs. Studies have shown that the 4‐chlorophenyltrifluoroborate potassium salt (4‐ClPTFBK) exhibits the most effective interaction with the perovskite lattice. Strong coordination between BF3−/halogen in anion and uncoordinated Pb2+/halide vacancies, along with the hydrogen bond between F in BF3− and H in FA+ are observed. Thus, due to the synergistic contribution of the potassium and anionic groups, the high‐quality perovskite film with large grain size and low defect density is achieved. As a result, the optimal devices show an enhanced efficiency of 24.50%, much higher than that of the control device (22.63%). Furthermore, the unencapsulated devices present remarkable thermal and long‐term stability, maintaining 86% of the initial PCE after thermal test at 80 °C for 1000 h and 95% after storage in the air for 2460 h. The researchers introduce a multifunctional potassium 4‐chlorophenyltrifluoroborate salt as additives for perovskite precursor to improve the performance perovskite solar cells by passivating defects, promoting crystallization process of the perovskite film and suppressing non‐radiative recombination in the film. The optimal devices show an enhanced efficiency of 24.50% with remarkable thermal and long‐term stability.