Phase Control of Cs‐Pb‐Br Derivatives to Suppress 0D Cs<sub>4</sub>PbBr<sub>6</sub> for High‐Efficiency and Stable All‐Inorganic CsPbBr<sub>3</sub> Perovskite Solar Cells
Jingwei Zhu, Benlin He, Xinpeng Yao, Haiyan Chen, Yanyan Duan, Jialong Duan, Qunwei Tang
Abstract
Abstract The precise phase control of Cs‐Pb‐Br derivatives from 3D CsPbBr 3 to 0D Cs 4 PbBr 6 highly determines the photovoltaic performance of all‐inorganic CsPbBr 3 perovskite solar cells (PSCs). Herein, the preferred phase conversion from precursor to Cs‐Pb‐Br derivatives is revealed by theoretically calculating the Gibbs free energies (∆ G ) of various phase conversion processes, allowing for a simplified multi‐step solution‐processable spin‐coating method to hinder the formation of detrimental 0D Cs 4 PbBr 6 phase and enhance the photovoltaic performance of a PSC because of its large exciton binding energy, which is regarded as a recombination center. By further accelerating the interfacial charge extraction with a novel 2D transition metal dichalcogenide ReSe 2 , the hole‐free CsPbBr 3 PSC achieves a champion efficiency of 10.67% with an impressive open‐circuit voltage of 1.622 V and an excellent long‐term stability. This work provides an in‐depth understanding on the precise Cs‐Pb‐Br perovskite phase control and the effect of derivatives on photovoltaic performance of advanced CsPbBr 3 PSCs.