High‐Performance Polarization‐Sensitive Mid‐Infrared Photodetection Based on a BP/PtSe ₂ van der Waals Heterostructure

Abstract Polarization‐sensitive mid‐infrared (MIR) photodetection is critical for applications such as astronomical observation, environmental monitoring, and biomedical imaging. However, conventional MIR photodetectors often require bulky optical systems, limiting their integration and power efficiency. Here, a high‐performance MIR polarization photodetector based on a two‐dimensional (2D) BP/PtSe 2 van der Waals (vdW) heterostructure is reported. The integration of anisotropic BP and isotropic PtSe 2 forms a highly asymmetric heterointerface, enabling efficient photocarrier separation and rapid transport. Benefiting from the strong built‐in electric field and excellent material properties, the device exhibits self‐powered operation at room temperature, with fast response times of 370/300 µs, a high specific detectivity of ≈2.5 × 10 9 cm Hz 0.5 W −1 , and a high polarization ratio of 0.9 in the 3.6–3.8 µm wavelength range. These results highlight the BP/PtSe 2 heterostructure as a promising platform for next‐generation, low‐power, high‐sensitivity, and polarization‐resolved MIR optoelectronic technologies.