Synthesis and stability of Cs-rich α phase Cs1-xDMAxPbI2Br(0 ≤ x ≤ 0.3) perovskite film

•1. Cs-rich α phase Cs1-xDMAxPbI2Br was synthesized for the first time.•2. Cs0.8DMA0.2PbI2Br still maintain good thermal and ultraviolet stability.•3. Compared with CsPbI2Br, the humidity stability of Cs0.8DMA0.2PbI2Br has been significantly improved. In this study, we successfully synthesized α-phase Cs1-xDMAxPbI2Br(0 ≤ x ≤ 0.3) without impurity and conducted device performance research and stability testing on it. The champion photoelectric conversion efficiency of α phase Cs0.8DMA0.2PbI2Br in inverted perovskite solar cells is 8.24 %. Compared with pure CsPbI2Br without DMA+, humidity stability of α-Cs0.8DMA0.2PbI2Br has been improved and it also maintains thermal and ultraviolet stability. This strategy shows bright application prospect for improving the stability of CsPbI2Br perovskite solar cells.