Dual-mode transparent synaptic device based on CsCu₂I₃ for neuromorphic computing and visual processing

Lead-free halide perovskite materials have attracted increasing attention for neuromorphic applications owing to their non-toxicity, photoresponsivity, and transport properties. Herein, a two-terminal optoelectronic synaptic device based on CsCu₂I₃ thin films was fabricated via a single-source thermal evaporation method. The ITO/CsCu₂I₃/Au device exhibited the versatile synaptic behaviours under both electrical and optical stimulation, benefiting from the excellent optoelectronic properties of CsCu₂I₃. Under electrical stimulation, the device achieved reliable resistive switching, low energy consumption (10.8 nJ), and a digit recognition accuracy of 97.17 %. Under optical stimulation, the device demonstrated reversible learning-forgetting-relearning behaviour, and frequency-dependent responses that enable high-pass filter for image sharpening. Notably, a classical Pavlovian conditioning process was successfully mimicked owing to its multi-wavelength photoresponsivity. This work provides a scalable and eco-friendly platform for multifunctional neuromorphic computing, in-sensor processing, and artificial perception systems.