Mixed‐Halide Inorganic Perovskite Solar Cells: Opportunities and Challenges

Abstract Recently, mixed‐halide inorganic CsPbI 3− x Br x perovskite solar cells (PSCs) have had a rapid advancement, which offers balanced efficiency, stability, tunable bandgap, and potential for indoor photovoltaic applications. Despite these advantages, significant challenges remain in the phase segregation phenomena, trap state density, and absorption range limitations. This review presents an analysis of the crystal and electronic structure and optical properties of CsPbI 3− x Br x , as well as an in‐depth look at high‐quality CsPbI 3− x Br x film preparation, phase segregation inhibition potential solutions, and interface engineering, highlighting the critical role of interface modification in the performance of CsPbI 3− x Br x PSCs. Furthermore, how CsPbI 3− x Br x PSCs can be strong candidates for indoor photovoltaics because of their adjustable bandgap that enables them to better match the absorption range and notable strength stability is discussed. Finally, the review provides perspectives to address the development bottlenecks and inspires future research prospects concerning CsPbI 3− x Br x PSCs.