Tailored Phase Transformation of CsPbI2Br Films by Copper(II) Bromide for High-Performance All-Inorganic Perovskite Solar Cells
Kai-Li Wang1, Rui Wang1, Zhao-Kui Wang1,2, *, Meng Li1, Yue Zhang1, Heng Ma3, Liang-Sheng Liao1, *, Yang Yang2, *
1Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Suzhou, Jiangsu 215123, China
3College of Physics and Electronic Engineering, Henan Normal University, Xinxiang 453007, P.R. China
All-inorganic-based perovskites achieved by replacing the organic component with cesium (Cs) have drawn more attention because of their intrinsic inorganic stability. However, the cell efficiency in all-inorganic perovskite solar cells is still far below that in organic-inorganic hybrid perovskite-based devices. Here, we develop a new strategy to mediate the CsPbI2Br crystallization by directly doping copper(II) bromide (CuBr2) into a perovskite precursor. The incorporation of CuBr2 played a role in retarding the crystallization dynamics process of CsPbI2Br film, resulting in a high-quality all-inorganic perovskite film with enlarged grain size, improved carrier mobilities, and reduced trap states. The fabricated perovskite solar cells delivered a champion power conversion efficiency of 16.15%, which is the highest efficiency in CsPbI2Br based all-inorganic perovskite solar cells and largely higher than 13.24% for pristine CsPbI2Br based device. The developed doping method paves a new route to fabricate high-performance all-inorganic perovskite solar cells.