Self-powered Artificial Optoelectronic Synapse Based on Leadfree Organic-Inorganic Hybrid Molecular Ferroelectric [C₄N₂H₁₄][BiI₅]

Abstract

This work demonstrates a self-powered artificial optoelectronic synapse based on the lead-free organic-inorganic hybrid molecular ferroelectric [C₄N₂H₁₄][BiI₅] (BDA-BiI₅). Leveraging its pronounced room-temperature ferroelectricity and efficient ferroelectric photovoltaic effect, the device operates without any external bias, enabling ultralow power consumption.Under light pulse stimulation, it successfully emulates essential synaptic plasticity behaviors, including paired-pulse facilitation, short-and long-term plasticity, and the transition from short-term to long-term memory. The fabricated artificial synapse also exhibits spike-rate-dependent plasticity, which is utilized to construct a high-pass filter for image sharpening.Furthermore, the device demonstrates associative learning capability through a Pavlovian conditioning experiment. These results highlight BDA-BiI₅ as an environmentally benign and multifunctional material for neuromorphic hardware, offering a promising route toward energy-efficient, bio-inspired visual perception systems.