“…In recent years, a wide range of approaches have been continued to improve the conversion efficiency and durability of perovskite solar cells, including the introduction of phase stabilizers into FA-based perovskite crystals, 1) the use of dopant-free hole transport polymer materials, 2) and surface treatment with n-type small molecule complexes. 3) In general, compositions of halide perovskite crystals are ABX 3 , consisting of A: organic cations, B: metal cations, and C: halogen anions. Perovskite solar cells with high conversion efficiencies often contain toxic lead, and the use of toxic lead is a problem for commercialization in terms of its impact on human health and the environment.…”