Time-Sequence Multifunctional Optoelectronic Synapse Enabled by a PtSe ₂ /α–In ₂ Se ₃ /MoS ₂ Ferroelectric Heterojunction

Optoelectronic devices are extensively studied in the fields of computing and memory. Two-dimensional ferroelectrics present an attractive platform for ultrathin integrations with enhanced functionality. This study reports an optoelectronic synapse based on a PtSe 2 /α–In 2 Se 3 /MoS 2 ferroelectric heterojunction that exhibits high-performance multistate memory and artificial synaptic behavior through effective modulation of ferroelectric polarization via electric-field-induced polarization and amplified light-induced depolarization effects. By strategically incorporating two active interfaces into the double heterojunction, the light-induced depolarization effect is remarkably amplified. This enables time-resolved encoded pulse recognition beyond spatial or intensity resolution. The device recognizes up to 8 time-sequence-encoded pulse states from “000” to “111”, with each state distinguished by over 500 pA. It also effectively emulates synaptic short-term plasticity and long-term potentiation during “Learning” and “Forgetting” processes, with tunable parameters such as light wavelength, power, and pulse number controlling the response. This device offers a promising approach to designing 2D ferroelectric heterojunctions for optoelectronic neuromorphic applications.