Self‐Powered Polarization‐Sensitive Photodetector Enabled by b‐AsP/Ta ₂ NiS ₅ /PtSe ₂ Van Der Waals Heterostructure

Near‐Infrared (NIR) photodetectors with high polarization sensitivity are essential for advanced optical sensing and imaging. However, achieving high responsivity and a large polarization ratio (PR) simultaneously remains challenging due to the limited availability of suitable infrared‐responsive anisotropic materials and efficient carrier transport pathways. Here, we present a self‐powered polarization‐sensitive NIR photodetector based on a b‐AsP/Ta 2 NiS 5 /PtSe 2 triple‐layer van der Waals (vdW) heterostructure. By integrating two anisotropic semiconductors (b‐AsP and Ta 2 NiS 5 ) with a type‐II Dirac semimetal PtSe 2 layer, our design synergistically enhances polarization selectivity and carrier transport. The staggered band alignment at the b‐AsP/Ta 2 NiS 5 interface induces a built‐in electric field that efficiently separates photogenerated carriers, while the PtSe 2 layer facilitates rapid carrier extraction, collectively suppressing recombination and enabling self‐powered operation. Under zero bias at 1550 nm, the device achieves a high responsivity of 0.52 A/W, an outstanding PR of 10.66, and a specific detectivity of 5.17 × 10 9 Jones. Moreover, the photodetector demonstrates excellent NIR imaging capabilities when integrated into a single‐point scanning imaging system. This work establishes a rational heterostructure engineering strategy for compact and energy‐efficient polarization‐sensitive NIR photodetectors.