Light-induced multilevel resistive switching in cesium-doped lead-free halide double perovskite memory device

A series of (CH3NH3)2-xCsxAgBiBr6 films (x=0, 0.1, 0.2, 0.3, 0.4) were fabricated on ITO/glass substrates through the sol-gel method. 15 % Cs doping (x=0.3) was the optimal condition for enhancing the film quality and achieving nonvolatile bipolar resistive switching (BRS) performance in the devices. The on/off ratio in the (CH3NH3)1.7Cs0.3AgBiBr6 (Cs-MAABB-3)-based RS device reached 7.7×104, high and low resistance states were maintained for over 104 s. Under different light intensities with a wavelength of 430 nm, six distinct resistance states were recorded at −0.3 V in the Au/Cs-MAABB-3/ITO/glass device. These multilevel states remained after 5000 s and 650 cycles, indicating the excellent retention and endurance of multilevel RS memory in the Au/Cs-MAABB-3/ITO/glass device. The RS behavior in this device followed the trap-controlled space charge-limited current and conductive filament models. Cs-doping increased the concentration of intrinsic vacancies appropriately, leading to a more prominent RS effect. With varying intensities of illumination, the change of Schottky-like barrier at the Au/Cs-MAABB-3 interface, modulated by the photo-induced carriers, affected the multilevel resistance states in the device. The excellent multilevel RS performance was observed for the first time in the Cs-MAABB-3-based device. It presents broad possibilities for improving high-density memory in lead-free halide double perovskite-based devices. [Display omitted] •The 15% Cs-doping at the A-site could improve the flatness and density of (CH3NH3)2AgBiBr6(MAABB) film.•Retention, endurance and the ON/OFF ratio in the 15% Cs doped MAABB (Cs-MAABB-3)-based RS memory were enhanced substantially.•Six levels of resistance states were exhibited in the Au/Cs-MAABB-3/ITO/glass device with different intensities of light.•.RS behavior was controlled by SCLC and CF models in the Cs-MAABB-3 layer under optical and electric fields.•.Reversible change in the Schttky barrier at the Au/Cs-MAABB-3 interface was also attributed to the RS behavior under light.