Artificial Synaptic Behavior of Lead-Free Cu₃Sb₂I₉ Perovskite Memristors

Lead-free perovskite memristors have garnered significant attention owing to their facile fabrication, exceptional memristive properties, solution processability, and environmental benignity. In this study, Cu₃Sb₂I₉ perovskite thin films were synthesized via a one-step spin-coating method and integrated as the functional layer in a vertically structured Ag/PMMA/Cu₃Sb₂I₉/FTO device. The device exhibits reproducible bipolar, nonvolatile resistive switching with high endurance (>3000 cycles) and stable retention characteristics. In addition, it emulates key biological synaptic functions, including excitatory and inhibitory postsynaptic currents (EPSC/IPSC) and paired-pulse facilitation/depression (PPF/PPD). Furthermore, cognitive processes such as learning, forgetting, and relearning can be mimicked by applying programmed voltage-pulse sequences. Notably, associative learning behavior was experimentally reconstructed through electronic emulation of Pavlovian conditioning paradigms, demonstrating the capability of the device to establish and extinguish conditioned responses. This work provides a strategy for constructing all-inorganic and lead-free perovskite materials for biomimetic synaptic devices.