Suppressing Phase Segregation in CsPbIBr₂ Films via Anchoring Halide Ions toward Underwater Solar Cells

Inorganic CsPbIBr₂ perovskite solar cells (PSCs) have accomplished many milestones, yet their progress has been constrained by ion migration and phase separation. This study explores the modulation of perovskite crystallization kinetics and halide ion migration through chlorobenzene (CB) antisolvent with bis(pentafluorophenyl)zinc (Zn(C₆F₅)₂) additive. The photoluminescence and absorption spectra reveal the significantly reduced phase segregaton in CsPbIBr₂ film treated by CB with Zn(C₆F₅)₂. Moreover, this research analyzes the CsPbIBr₂ film's free carrier lifetime, diffusion length, and mobility using time-resolved microwave conductivity and transient absorption spectroscopy after Zn(C₆F₅)₂ modification. Consequently, the modified CsPbIBr₂ PSCs offer a 12.57% power conversion efficiency (PCE), the highest value among CsPbIBr₂ PSCs with negligible hysteresis and prolonged stability. Furthermore, under 1-m-deep water, CsPbIBr₂ PSCs display a PCE of 14.18%. These findings provide an understanding of the development of phase-segregation-free CsPbIBr₂ films and showcase the prospective applications of CsPbIBr₂ PSCs in underwater power systems.