Anisotropy‐Driven Carrier Transport Modulation in Stacking‐Engineered Ta ₂ PdS ₆ /ReSe ₂ Van der Waals Heterostructures Photodetectors

Abstract Polarization‐sensitive photodetection based on anisotropic/anisotropic, namely all‐anisotropic, van der Waals heterostructures (vdWHs) offers transformative potential for miniaturized multifunctional optoelectronics, yet progress is hindered by low polarization ratios (<10) and an incomplete understanding of performance‐governing mechanism. Here, these limitations are addressed by engineering type‐I Ta 2 PdS 6 /ReSe 2 vdWHs with orientation‐tailored architectures, featuring a unilateral depletion region to modulate carrier transport dynamics. By systematically comparing parallel and vertical stacking configurations, the parallel configuration delivers exceptional self‐powered performance under 635 nm light illumination: responsivity of 482 mA/W, specific detectivity of 1.0 × 10 12 Jones, and polarization ratio of 11.21, nearly one order of magnitude higher than its vertical counterpart and other reported all‐anisotropic vdWHs. Mechanistic studies attribute these enhancements to synergistic effects of optimized carrier pathways along the armchair directions of both materials and a strengthened built‐in electric field within a narrowed transition region, collectively suppressing interlayer nonradiative recombination and boosting efficient photocarrier extraction. Integration into polarized single‐pixel imaging and polarization‐coded optical communication systems demonstrates the versatility of this approach. These results establish orientation engineering as a powerful strategy for unlocking the full potential of 2D all‐anisotropic vdWHs in a next‐generation multifunctional optoelectronic platform.