Low-Voltage Resistive Switching and Synaptic Plasticity in Cs2AgBiBr6 Memristors.

Synaptic devices that can store and process data are imperative to mimic the operation of the human brain. In this work, lead-free double perovskite Cs2AgBiBr6 memristors were fabricated on ITO/glass substrates with thermally evaporated Ag top electrodes and systematically investigated for their resistive switching (RS) and neuromorphic functionalities. The devices exhibit stable, low-voltage (+0.239 ± 0.018 V) volatile resistive switching with good cycle-to-cycle reproducibility. A maximum ON/OFF ratio exceeding 105 is maintained for 24 cycles, while values above 102 persist for 1100 cycles. Electrical analysis reveals that the switching behavior is governed by ion migration-induced filament formation, primarily involving mobile Br- ions, VBr+ vacancies, and Ag+ ions injected from the electrode. A detailed conduction model is proposed based on space charge-limited conduction and ion-induced electric field screening. Furthermore, the volatile RS characteristics enable biologically inspired synaptic functions, including spike amplitude-dependent plasticity (SADP), spike number-dependent plasticity (SNDP), and paired-pulse facilitation (PPF) with a maximum facilitation index of 169%, benchmarking competitively among perovskite memristive synapses. Based on experimentally extracted synaptic weight-update rules, an artificial neural network simulation achieved a peak recognition accuracy of 98%.