Bidirectional Self‐Powered Photoresponse in GeS _x Se _1‐x /WSe ₂ van der Waals Heterostructures for Advanced Neuromorphic Vision Systems

Abstract Bidirectional optoelectronic devices, capable of emulating the neurobiological functions of retinal neurons, hold great promise for artificial neuromorphic vision systems. However, a systematic approach to achieving a wide range of modulation of bidirectional photoresponse properties remains unexplored. Here, the modulation of bidirectional photoresponse characteristics in 2D GeS x Se 1‐x /WSe 2 (0 ≤ x ≤ 1) van der Waals heterostructures (vdWHs) through alloy engineering is demonstrated. In GeS 0.2 Se 0.8 /WSe 2 vdWHs, a highly reconfigurable responsivity ranging from 289.84 to −934.11 mA W −1 with bidirectional photoresponse is achieved—nearly two orders of magnitude greater than that of binary GeSe/WSe 2 vdWH (0.9 to −17.34 mA W −1 ). Additionally, the GeS 0.2 Se 0.8 /WSe 2 device exhibits a linearly gate‐driven bidirectional responsivity within an optimal voltage window of 20 V. This tunability in polarity photoresponse performance is attributed to the band alignment‐induced band offset evolution and Fermi level variations driven by changes in sulfur content. Furthermore, when integrated with spiking neural networks, the GeS 0.2 Se 0.8 /WSe 2 vdWH device enables dynamic vision system simulations, achieving exceptional motion perception with a recognition accuracy of ≈99%. This advancement in reconfigurable bidirectional optoelectronic devices paves the way for high‐accuracy and high‐efficiency neuromorphic vision sensors.