Inorganic CsPbI2Br halide perovskites: from fundamentals to solar cell optimizations

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.

Automated summary

Inorganic CsPbI2Br halide perovskites are extensively studied as absorber layers for solar cells due to their high thermal and phase stability. However, CsPbI2Br solar cells face challenges including poor film morphology, large energy offset at the interfaces with charge transporting layers or carbon electrodes, large tensile strain, and degradation caused by hygroscopic dopants in the hole transporting layer. This review provides fundamental knowledge on CsPbI2Br perovskites and reviews the recent developments in CsPbI2Br perovskite solar cells through film optimization, charge transporting layer optimization, interface engineering, etc. The authors discuss the challenges, optimization methodologies, and present conclusions and future outlook for developing highly efficient and stable CsPbI2Br solar cells.