A low-energy consuming, optically and electrically stimulated artificial synapse based on lead-free metal halide perovskite (Cs3Cu2I5) for neuromorphic applications

Abstract

Computational systems inspired by the human brain are being researched to minimize high power consumption and memory instability in traditional computers. Metal halide perovskites, having high light absorption and tunable bandgap, can precisely modulate electrical conductivity and are therefore considered as an ideal candidate for memory and neuromorphic applications. An all-inorganic lead-free metal halide perovskite (Cs₃Cu₂I₅) based optoelectronic synaptic device has been developed, demonstrating the potential for memory storage and neuromorphic computing. The two-terminal Au/Cs₃Cu₂I₅/Au based capacitive-coupled memory device is a low-energy consuming device with energy consumption of ∼1–200 pJ. The device shows extremely stable memory with a ON/OFF ratio of 10 between a high-resistance state and a low-resistance state with endurance of up to 8000 cycles of operation. The device exhibits a range of critical synaptic functions upon stimulation with optical (UV, 375 nm) and electrical voltage spikes. The biological synaptic functionalities like excitatory post-synaptic current (EPSC), inhibitory post-synaptic currents (IPSC), short-term plasticity (STP) to long-term plasticity (LTP) transition, paired-pulse facilitation (PPF), spike-number dependent plasticity (SNDP), spike-rate dependent plasticity (SRDP) and spike-voltage dependent plasticity (SVDP) are successfully replicated. This study demonstrates the use of non-toxic inorganic metal halide perovskite as an efficient optoelectronic artificial synapse with excellent memory and the potential to be used for next-generation neuromorphic computers.