Infrared Polarization‐Sensitive Visual Neuromorphic Synapse Based on 2D PdSe ₂ /Ta ₂ NiS ₅ Heterojunction

ABSTRACT Polarization‐based visual detection overcomes the limitations of conventional vision systems by providing additional optical polarization information for accurate target recognition and environmental assessment in critical scenarios. However, current neuromorphic vision systems lack adequate polarization sensitivity in the infrared band and cannot support integrated “broad‐spectrum polarization perception and brain‐inspired processing”. To address this, high‐performance polarization‐sensitive infrared neuromorphic synaptic devices are urgently needed. This study designs a 2D PdSe ₂ /Ta ₂ NiS ₅ heterojunction, taking advantage of the pronounced in‐plane anisotropy and narrow bandgap inherent to PdSe ₂ and Ta ₂ NiS ₅ . Through bias‐induced band bending, the electronic properties are modulated to achieve photoelectric synaptic functionality. The heterojunction demonstrates a broad spectral response from 808 to 2200 nm, with a high polarization ratio of 15.6 at 808 nm and 8.7 at 2200 nm. It successfully emulates key synaptic behaviors such as paired‐pulse facilitation (PPF = 56% at 808 nm), paired‐pulse depression (PPD), and the transition from short‐term to long‐term plasticity (STP to LTP), while consuming only 153.2 fJ per synaptic event. Synaptic weight can be dynamically modulated via light intensity, pulse width, and polarization angle. This heterojunction shows great potential for applications in autonomous driving, industrial infrared inspection, and bionic navigation.