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

In this work, we prepared lead-free Cs3Bi2I9-xBrx (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/Cs3Bi2I9-xBrx/ITO structure. These memristors exhibited non-volatile and bipolar resistance switching behavior without electroforming. Notably, the bandgap of the Cs3Bi2I9-xBrx (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/Cs3Bi2I9-xBrx/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.