Surface Engineering toward High-Performance CsPbI₃ Perovskite Solar Cells

Inorganic CsPbI₃ perovskite solar cells (PSCs) have attracted intense attention due to higher chemical stability and exceptional optoelectronic properties. However, tremendous intrinsic defects in CsPbI₃ perovskite have induced serious charge recombination loss, which greatly suppresses device performance. To address the issue, surface engineering has been widely used to passivate the intrinsic defects, which has well promoted the power conversation efficiency (PCE) of CsPbI₃ PSCs to over 21%. In this Forum Article, recent progress in surface engineering for CsPbI₃ perovskite is systematically summarized, discussed, and categorized in the following aspects: molecular modification, ion termination, in situ generation of the second phase, and direct introduction of the second phase. Finally, we present a brief outlook about challenges and opportunities of surface engineering for CsPbI₃ perovskite.