Deep‐Ultraviolet Photoactivation‐Assisted Contact Engineering Toward High‐Efficiency and Stable All‐Inorganic CsPbI2Br Perovskite Solar Cells

Abstract

All‐inorganic perovskite CsPbI2Br have been regarded as a promising candidate to tackle the thermal instability issue of organic–inorganic perovskite solar cells. However, the serious interfacial charge recombination and large voltage potential loss in cells circumscribe their performance and commercialization. Herein, a facile approach is demonstrated in which the SnO2 electron transport layer is modified with short‐period deep‐ultraviolet (DUV) photoactivation process to decrease the work function and achieve better energy alignment with the conduction band of perovskites. Such modification triggers efficient charge transfer and reduces the charge recombination. Moreover, first‐principles calculation further demonstrates that DUV‐treated SnO2 can strengthen the interface interaction, reduce the interface stress caused by lattice mismatch, induce more ordered perovskite structure, enlarge transfer charge from 0.71 to 2.33 e, gain larger built‐in field (from 0.74 to 2.09 eV), lower work function, and smaller conduction band offset. Thus, all‐inorganic CsPbI2Br solar cells based on DUV‐treated SnO2 exhibit a significant enhancement in power conversion efficiency, and the champion cell achieves an elevated efficiency of 15.1% with a superior Voc of 1.22 V and better stability.