Inorganic CsPbI2Br halide perovskites: from fundamentals to solar cell optimizations

Abstract

Inorganic CsPbI₂Br halide perovskites have been widely explored as absorber layers for solar cell applications due to their higher thermal and phase stability. However, the CsPbI₂Br solar cells experience several problems, such as (i) a poor CsPbI₂Br film morphology, (ii) a large energy offset at the CsPbI₂Br/charge transporting layers (CTLs) or CsPbI₂Br/carbon electrode interfaces, (iii) large tensile strain between the CsPbI₂Br and CTLs and (iv) addition of hygroscopic dopants in the commonly used hole transporting layer (HTL) accelerating the device degradation process. This review article is dedicated to providing fundamental knowledge of inorganic CsPbI₂Br halide perovskites, as well as an up-to-date review on the development of CsPbI₂Br perovskite solar cells (PSCs) from 2021 to 2022 through optimization of CsPbI₂Br films, optimization of CTLs, interface engineering, etc. The authors start by discussing the challenges in CsPbI₂Br PSCs, followed by the optimization methodologies to gain highly efficient and stable CsPbI₂Br PSCs. Finally, conclusions and future outlook are presented for developing CsPbI₂Br PSCs with high efficiency and superior stability.