High-quality organic–inorganic lead-free bismuth halide perovskite film for resistive switching memory application

Bismuth-based lead-free perovskite is one of the most popular research fields in halide perovskites. However, due to the valence of Bi³⁺, Bi-based perovskite has non-cubic crystal structure, causing the film quality poor and hindering further applications. In this work, taking advantage of long-chain organic cation, i.e., phenylethylamine cation, (PEA⁺), we have fabricated high-quality bismuth halide perovskite (PEA)₃Bi₂I₉ film, assisted by vacuum treatment, and investigated the characteristic differences between Cs₃Bi₂I₉ and (PEA)₃Bi₂I₉. First-principle calculation has been employed next, which distinguishes the discrepancies theoretically and confirms the experimental results. Furthermore, resistive switching memory devices based on high-quality (PEA)₃Bi₂I₉ film have been fabricated, and clear resistive switching behaviors are observed, showing ON/OFF ratio about 100 and retention time above 10³ s.