Sandwiched Halogen Perovskite as Sensitizing Floating Gate for Reconfigurable Optoelectronic Synapses

Optoelectronic synapses can emulate the functions of biological synapses with high-speed, low-power, compact, and fault-tolerant advantages, enabling retinomorphic sensing and biomimetic machine vision applications. High photoresponsivity and reconfigurable synaptic plasticity are vital for optoelectronic synapses. Low-dimensional materials are often used as a phototransistor channel, offering advantages such as atomic-scale thickness, high carrier mobility, and band gap tunability, yet their limited light absorption due to ultrathin structures restricts the photoresponsivity. Halide perovskites, renowned for strong light absorption, long carrier lifetime, and long diffusion length, present a synergistic solution when integrated with low-dimensional systems. Here, the intrinsic performances and full potentials of halogen perovskite-sensitized optoelectronic synapses are systematically assessed by TCAD simulations. A synaptic device architecture with halide perovskites as a sandwiched floating gate is compared with conventional gate- or channel-adjacent sensitizing perovskite layers. Owing to the mitigated surface recombination and Fermi-level pinning, the sandwiched perovskite floating gate design achieves enhanced photoresponsivity, broader dynamic response range, and symmetric reconfigurable excitatory/inhibitory photocurrent, benefiting the reconfigurable optoelectronic synapses with higher light sensitivity, lower power consumption, and larger plasticity weight modulation range for biomimetic machine vision system applications.