Lead-Free Layered Halide Double Perovskites with Aromatic Organic Cations for Resistive Switching Memories and Artificial Synapses

The realization of efficient and compact artificial visual systems requires integration of sensing, memory, and computing within a single device, avoiding the limitations of conventional architectures that rely on separate sensors, memory arrays, and processors. Neuromorphic devices inspired by the human nervous system offer a path forward by merging these functions. Halide perovskite-based memristors are particularly promising for this purpose owing to their mixed ionic-electronic conduction and inherent light sensitivity. However, toxicity and long-term instability of lead-based perovskites remain barriers to practical use. In this work, we demonstrate a family of lead-free layered double perovskites incorporating aromatic cations, as environmentally friendly multifunctional materials for neuromorphic electronics. These compounds combine the structural advantages of DJ & RP phases with the defect chemistry of Ag/Bi-based double perovskites to yield stable and tunable device behavior. By systematically tuning composition and device architecture, both volatile and non-volatile resistive switching are realized. Beyond electrical synaptic emulation, the intrinsic light sensitivity of these layered halide perovskites is harnessed to demonstrate optical synaptic behavior. In solar-cell configurations, the devices further respond without any external bias, functioning in a self-powered manner and highlighting their potential for zero-standby-power in-sensor computing.