Understanding the synergistic influence of the propylammonium bromide additive and erbium-doped CsPbI2Br for highly stable inorganic perovskite solar cells

Abstract

Inorganic cesium lead halide perovskites have gained increasing attention to boost photovoltaic performance and device stability. Nevertheless, the photoactive to photo-inactive phase transition under ambient conditions hampers its further enhancement. Here, we varied various amounts of propylammonium bromide (PABr) additive in the CsPbI₂Br perovskite and further varied the erbium (ErCl₃)-doped CsPbI₂Br (herein CsPb_1−nEr_nI₂BrX_n) (where X = Cl; 0 ≤ n < 1) perovskite. Further, in the optimized (CsPb_0.97Er_0.03I₂BrCl_0.09) composition, we studied the influence of various amounts of the PABr additive. Our results clearly show the PABr additive added film results in high-quality surface morphology, high crystallinity, and decreased trap-state density. Accordingly, our champion CsPb_0.97Er_0.03I₂BrCl_0.09 + 2 mg ml⁻¹ PABr (CsEr-PA)-based inorganic perovskite solar cell (IPVSC) device showed 16.74% power conversion efficiency (PCE), which is much higher than that of bare (13.20%) and CsPb_0.97Er_0.03I₂BrCl_0.09-based perovskite devices (15.73%). In addition, the CsEr-PA-based IPVSC device revealed increased long-term stability, which maintained 90% of its initial PCE at 65 °C and thermal stress of over 400 h under ambient conditions. These dual stabilization strategies cover a new way to increase the photovoltaic performance of IPVSCs.