Enhanced performance of BiI-incorporated CsPbBr solar cells.

CsPbBr all-inorganic perovskite solar cells (PSCs) have been extensively investigated due to their remarkable stability. However, their limited film quality and wide bandgap result in a low photoelectric conversion efficiency (PCE). In this study, BiI was incorporated into CsPbBr films to synergistically enhance light absorption and film quality. It was found that the partial substitution of Pb and Br with Bi and I in CsPbBr improved film quality, enhanced light absorption, and facilitated charge transfer and extraction. The device incorporating BiI-incorporated CsPbBr as a light absorbing layer achieved an efficiency of 9.54%, exhibiting a significant enhancement of 19.4% compared to the undoped device. This work provides a new incorporating strategy that collaboratively improves light absorption and film quality.