Ambient-stable and lead-free Cs3Bi2I9−xBrx (0 ≤ x ≤ 9) perovskite films for memristor devices

Abstract

In this work, we prepared lead-free Cs₃Bi₂I_9−xBr_x (x = 0, 1, 2, 3, 6, and 9) thin films using a green anti-solvent method under air conditions and used them to fabricate memristors with an Al/Cs₃Bi₂I_9−xBr_x/ITO structure. These memristors exhibited non-volatile and bipolar resistance switching behavior without electroforming. Notably, the bandgap of the Cs₃Bi₂I_9−xBr_x (x = 0, 1, 2, 3, 6, 9) series films was regulated by bromine doping. The switching ratio of devices changed with the films' band gap and increased from 10² to 10³. The resistance state of the Al/Cs₃Bi₂I_9−xBr_x/ITO devices was maintained even after 150 switching cycles and 10⁴ seconds of reading. Moreover, the Al/Cs₃Bi₂Br₉/ITO memristor showed excellent stability in the air after 100 days. This study offers beneficial insights into designing perovskite materials and regulating the performance of perovskite memristors.