Resistive Switching in Nonperovskite-Phase CsPbI₃ Film-Based Memory Devices

Because of their attractive photoelectrical properties, perovskite-phase, CsPbX₃ (X = I, Br, or Cl) materials have recently gained attention for their applications in resistive switching (RS) memories. However, phase transition of the CsPbI₃ from perovskite (cubic phase) to nonperovskite (orthorhombic phase) at room temperature is problematic; it remains a challenge to apply nonperovskite CsPbI₃ in RS memories. In the present work, a polymethylmethacrylate (PMMA)-assisted deposition method for nonperovskite CsPbI₃ is introduced to fabricate a composite film of CsPbI₃ with PMMA (PMMA@CsPbI₃) with a smooth surface morphology on fluorine-doped tin oxide (FTO) substrates. Devices with a Ag/PMMA@CsPbI₃/FTO architecture show nonvolatile RS characteristics with an ON/OFF ratio around 10², endurance over 500 cycles, and a retention time of 10³ s. Analyses suggested that a Schottky barrier at the Ag/PMMA@CsPbI₃ interface and a bias-induced migration of Ag ions within the composite films are responsible for the RS operation. This is the first record for RS devices based on nonperovskite CsPbI₃, and it may bring the future research on nonperovskite CsPbI₃ applied in RS memory devices some new inspiration..