Excellent Moisture Stability and Efficiency of Inverted All-Inorganic CsPbIBr₂ Perovskite Solar Cells through Molecule Interface Engineering

All-inorganic lead halide perovskite solar cells (PSCs) have drawn widespread interest because of its excellent thermal stability compared to its organic–inorganic hybrid counterpart. Poor phase stability caused by moisture, however, has thus far limited their commercial application. Herein, by modifying the interface between the hole-transport layer (HTL) and the perovskite light absorption layer, and by optimizing the HTL for better energy alignment, we controlled the growth of perovskite, reduced carrier recombination, facilitated carrier injection and transport, and improved the PSC’s power conversion efficiency (PCE) and moisture stability. When testing using a positive bias scan, we obtained a significant improvement in PCE, 9.49%, which is the champion efficiency of CsPbIBr₂-based inverted PSC at present. The stability measurement shows that the passivated CsPbIBr₂-based inverted PSCs can retain 86% of its initial efficiency after 1000 h preserved in ambient air with 65% relative humidity. This study paves a new way for enhancing the moisture stability and power conversion efficiency of CsPbIBr₂-based PSCs.