Resistive Switching Characteristics Improved by Visible-Light Irradiation in a Cs₂AgBiBr₆-Based Memory Device

Light-modulated lead-free perovskites-based memristors, combining photoresponse and memory, are promising as multifunctional devices. In this work, lead-free double perovskite Cs₂AgBiBr₆ films with dense surfaces and uniform grains were prepared by the low-temperature sol-gel method on indium tin oxide (ITO) substrates. A memory device based on a lead-free double perovskite Cs₂AgBiBr₆ film, Pt/Cs₂AgBiBr₆/ITO/glass, presents obvious bipolar resistive switching behavior. The R_OFF/R_ON ratio under 445 nm wavelength light illumination is ~100 times greater than that in darkness. A long retention capability (>2400 s) and cycle-to-cycle consistency (>500 times) were observed in this device under light illumination. The resistive switching behavior is primarily attributed to the trap-controlled space-charge-limited current mechanism caused by bromine vacancies in the Cs₂AgBiBr₆ medium layer. Light modulates resistive states by regulating the condition of photo-generated carriers and changing the Schottky-like barrier of the Pt/Cs₂AgBiBr₆ interface under bias voltage sweeping.