Comprehensive assessment of all-inorganic CsPbI_3–xBr_x perovskite-based solar cells: Interface engineering, stability, and economic aspects

All-inorganic perovskite materials based on CsPbI_3–xBr_x (x = 0, 1, 2, and 3) have garnered considerable attention from the photovoltaic (PV) community on account of their superior resistance to moisture and temperature in comparison to organic–inorganic hybrid (OIH)-perovskite solar cells (PSCs). Since the initial report in 2015, extensive research and ongoing preparation process optimization have led to a substantial improvement in the power conversion efficiency (PCE) of CsPbI_3–xBr_x PSCs, from 2.9 % to over 21.5 %. Nevertheless, the device PCE of PSCs based on CsPbI_3–xBr_x remains inferior to that of OIH-PSCs. As a result, significant efforts are being made to increase the overall PCE of CsPbI_3–xBr_x PSCs through the synergistic optimization of the perovskite layer and device interfaces. In this review, a comprehensive discussion is made on the stability of the material against thermal and high moisture environments, followed by a thorough analysis of the methodologies for fabricating pinhole-free and uniform CsPbI_3–xBr_x films. The recent development of all-inorganic CsPbI_3–xBr_x PSCs based on interface engineering is overviewed, followed by a detailed discussion on the commercial viability of the CsPbI_3–xBr_x PSCs. Finally, some suggestions on overcoming development bottlenecks are presented to obtain an understanding of CsPbI_3–xBr_x PSCs and encourage future research opportunities.