Dual-Interface Engineering of Cs2CuBiBr6-Based Memristive Synaptic Devices for Neuromorphic Computing

Pb-free double perovskite Cs2CuBiBr6 (CCBB)-based resistive random-access memory (ReRAM) synaptic devices are developed using a dual-interface engineering approach to achieve stable resistive switching and neuromorphic functionality. High-quality CCBB thin films are obtained via optimized antisolvent-assisted crystallization, enabling enhanced crystallinity and reduced defect-induced energetic disorder. Modification of the bottom interface with a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) interlayer improves CCBB film continuity and provides a more favorable environment for homogeneous charge injection. The introduction of an ultrathin bathocuproine (BCP) interlayer at the top interface regulates the spatial redistribution of Ag-related species. The cooperative regulation of charge injection and Ag-related electro-ionic processes promotes more reproducible formation and rupture of localized conductive pathways, resulting in improved switching stability and device-to-device reproducibility. The CCBB-based ReRAM exhibits reliable bipolar resistive switching over 600 cycles, an on/off current ratio of approximately 103, and stable data retention up to 104 s. Gradual and repeatable conductance modulation under electrical pulse stimulation further demonstrates synaptic potentiation and depression behaviors. MNIST-based neural network simulations reveal excellent neuromorphic performance, with up to 90% recognition accuracy. This work highlights cooperative dual-interface regulation of charge injection and Ag-related electro-ionic processes as an effective design strategy for achieving reliable Pb-free perovskite ReRAM and neuromorphic synaptic operation.