Resistive switching and artificial synaptic performances of memristor based on low-dimensional bismuth halide perovskites

Zero-dimensional (0D)-Cs₃Bi₂I₉, two-dimensional (2D)-Cs₃Bi₂Br₉, and one-dimensional (1D)-Cs₃Bi₂Cl₉ perovskite films have been successfully grown on indium tin oxide (ITO) glass substrates, which were used to fabricate memristors with the structure of Al/Cs₃Bi₂X₉ (X = I, Br, and Cl)/ITO glass. The current three types of memristors exhibited bipolar resistive switching behaviors. Both the endurance and retention time tests clearly demonstrated the excellent stability of present devices. Especially, the ON/OFF ratio of the 0D-Cs₃Bi₂I₉ device is close to 10⁴ at the reading voltage of 0.1 V, which is nearly 100 and 1000 times larger than those of the 1D-Cs₃Bi₂Cl₉ device and the 2D-Cs₃Bi₂Br₉ device, respectively. The activation energy of halide vacancies in the Cs₃Bi₂X₉ (X = I, Br, and Cl) films was calculated using the density functional theory by considering a minimum migration path, demonstrating the dimensionality of the Cs₃Bi₂X₉ (X = I, Br, and Cl) film affected the formation and rupture of conductive filaments. Moreover, the short-term plasticity and long-term plasticity of biological synapse were simulated by evaluating the conductance responses of Al/Cs₃Bi₂X₉ (X = I, Br, and Cl)/ITO devices under various voltage pulses in detail. The duration time of long-term plasticity in all the present devices can last for up to 250 s. The 0D-Cs₃Bi₂I₉ device showed both the highest spike-duration-dependent plasticity and paired-pulse facilitation indexes compared to the other two devices. Additionally, the 0D-Cs₃Bi₂I₉ device successfully established the associative learning behavior by simulating the Pavlov’s dog experiment.