Alloying Sb into all inorganic lead-free CsBi3I10 for improving the crystal growth and photovoltaic performance

Abstract

The all-inorganic lead-free perovskite CsBi₃I₁₀ has recently emerged as a promising light absorber. However, the poor morphology of CsBi₃I₁₀ film remains a critical issue for fabricating high-performance solar cells. In this work, we report an ion substitution strategy by alloying Sb into CsBi₃I₁₀, resulting in dramatically improved grain crystallinity and markedly reduced bandgaps for better light utilization. The Sb-substituted CsBi₃I₁₀ film composed of highly-crystalline large grains can form a bulk-heterojunction structure with the electron acceptor PCBM to facilitate the exciton separation. With PTAA as the hole transport layer, the solar cell assembled using Cs(Bi_0.7Sb_0.3)₃I₁₀ can afford a champion power conversion efficiency of 1.54% with a high V_oc of 0.81 V.