Synergistic Dual-Mechanism Self-Powered Photodetector with Broadband Polarization Sensitivity for Multifunctional Applications.

Two-dimensional (2D) photodetectors are a research focus in optoelectronics owing to their excellent flexibility and integration. However, conventional 2D photodetectors typically rely on a single photoresponse mechanism, and studies on synergizing multiple physical mechanisms to enhance detection performance remain insufficient. Herein, we demonstrate a high-performance self-powered Gr/InSe/MoS2 van der Waals heterojunction photodetector with a unilateral depletion n-n junction. By rationally integrating graphene, InSe, and MoS2, the device realizes remarkable synergistic enhancement by dual-mechanism of photovoltaic and photothermoelectric effects. Benefiting from the thermoelectric field induced by the temperature gradient in MoS2 aligns with the built-in field of the n-n junction, effectively promote efficient photocarrier separation and significantly improving the photoresponse. Under zero-bias operation, it exhibits a broadband photoresponse from 355 to 1064 nm, a peak responsivity of 650 mA W-1 at 532 nm, an ultralow dark current of 5.3 × 10-13 A, and a fast rise time of 15.6 μs. Meanwhile, the device displays distinct polarization sensitivity originating from the in-plane anisotropy of InSe. It is successfully applied to image encryption, polarization imaging, and near-infrared optical communication, providing a promising strategy for designing advanced multifunctional self-powered photodetectors.