Air-processed FA–Cs perovskite scalable films without Pb0 defects for efficient inverted photovoltaic modules

Abstract

Metallic lead (Pb⁰) defects in halide perovskites act as deep-level traps, serve as charge-recombination centers, and accelerate crystal structure degradation. Here, blade coating under ambient air conditions is employed to scalably fabricate FA–Cs perovskite films for inverted photovoltaic modules. During this process, (CH₃)₃SI is incorporated to interact with the surplus PbI₂, resulting in the formation of a one-dimensional (1D) (CH₃)₃SPbI₃ phase and suppressing harmful Pb⁰ defects. The 1D phase can optimize energy-level alignment, reduce defect states, inhibit carrier recombination, and enhance carrier transport. By optimizing the (CH₃)₃SI concentration, the power conversion efficiency of perovskite modules on a 10 × 10 cm² substrate is enhanced from 18.25% to 19.98%, accompanied by improved open-circuit voltage and fill factor. Besides, the hysteresis index is reduced from 0.09 to 0.02. Additionally, the unencapsulated modules retain approximately 90% of their initial efficiency after 1000 hours, whereas the control devices maintain only 84% after 740 hours.