Near-Infrared Photodetection Enabled by Interface-Purified WS2/MoTe2 Heterojunctions via Dual hBN Encapsulation

High-performance near-infrared photodetection is of great importance for applications in optical communication and imaging. Here, a vertically stacked WS2/MoTe2 van der Waals heterojunction with dual hBN encapsulation is constructed. Benefiting from interface purification and synergistic band structure modulation, the device exhibits significantly enhanced photoconversion efficiency and an extended spectral response range. A high responsivity of 13021 A W-1 and a detectivity of 5.39 × 1014 Jones are achieved at 405 nm. In the near-infrared region, responsivities of 586 A W-1 and 2292 A W-1 are obtained at 808 nm and 1064 nm, respectively, with a maximum detectivity of 9.49 × 1013 Jones. Stable time-response characteristics are maintained across all measured wavelengths. These results demonstrate that interfacially purified van der Waals heterostructures provide an effective strategy for high-performance two-dimensional near-infrared photodetectors.