Ultrasensitive Optoelectronic Synapse in Mixed‐Dimensional CuInSe 2 Nanowires/MoS 2 Heterostructures

ABSTRACT Mixed‐dimensional semiconductor heterostructures offer a compelling platform for combining photodetection with optoelectronic synaptic functionalities through controlled photocarrier dynamics. Here, we report catalyst‐free chemical vapor deposition growth of p‐type one‐dimensional CuInSe 2 (CIS) nanowires and their integration with n‐type two‐dimensional MoS 2 to construct mixed‐dimensional p‐n heterojunctions. Individual CIS nanowires exhibit pronounced defect‐assisted photoconductive gain and optoelectronic synaptic behaviors, yet suffer from high dark current that limits weak‐light detection. By establishing a CIS/MoS 2 heterostructure, the band alignment promotes the transition from majority hole conduction in CIS to electron‐dominated conduction in the heterostructure, resulting in strong suppression of dark current and markedly enhanced optoelectronic performance, including a responsivity up to 2286 A·W −1 , an ultrahigh detectivity of 9.29 × 10 12 Jones, and external quantum efficiency exceeding 4.45 × 10 5 %, while retaining the short‐term memory functionalities. Leveraging this short‐term memory response as a temporal preprocessing layer, the synaptic heterostructure device enables device‐calibrated simulations for proof‐of‐concept visual‐processing tasks in handwritten‐digit classification, motion‐direction recognition, and next‐position prediction. This work establishes carrier‐dynamics engineering in 1D/2D p‐n heterostructures as an effective strategy to connect photodetection with neuromorphic optoelectronics.