Artificial Vision Synapse with Improved Temperature Stability Enabled by Ag/MoTe ₂ /Graphene Vertical Heterojunction for Enhanced Photodetection and Synaptic Plasticity

The plasmonic hot-electron effect is key to advancing multifunctional photodetection, enhancing light – matter interactions, boosting absorption and detection sensitivity, and extending wavelength ranges and spectral responses. In two-dimensional vertical heterojunctions with short carrier migration distances, their role in optimizing photodetection and regulating visual synapses is a critical frontier. This paper proposes an Ag/MoTe 2 /graphene (Gr) vertical heterojunction with codirectional built-in electric fields at Ag/MoTe 2 and MoTe 2 /Gr interfaces for efficient carrier transport, where the Ag electrode introduces the plasmonic hot-electron effect as the key to enhanced performance, extending the self-powered infrared detection range to 1550 nm and achieving a responsivity of up to 0.3 A/W under 660 nm light illumination. Notably, the heterojunction exhibits excellent visual synaptic performance, including tunable plasticity dependent on parameters, PPF modulation, and ultralow energy consumption of 1.5 pJ per spike. Within the temperature range 300–340 K, enhanced phonon scattering partially suppresses the plasmonic hot-electron effect, thereby reducing the impact of temperature rise on the synaptic current. The Ag/MoTe 2 /Gr vertical heterojunction shows good temperature stability over the Gr/MoTe 2 /Gr vertical heterojunction, confirming its potential for building thermally stable neuromorphic vision systems and self-powered optoelectronics.