High‐Performance Self‐Driven Polarization‐Sensitive Imaging Photodetectors based on Fully Depleted T‐MoSe₂/GeSe/B‐MoSe₂ Van der Waals Dual‐Heterojunction

Abstract New 2D materials with low‐symmetry structures aroused great interest in developing monolithic polarization‐sensitive photodetectors with small volumes, which can provide a new degree of freedom for more information in night, fog, and smoke environments. However, at least half of them presented a small anisotropy with an anisotropic factor (≈2) of photocurrent up to now. Herein, after systematic investigation of the optical anisotropies of GeSe nanosheets, a novel self‐driven polarization‐sensitive imaging photodetector with excellent performance based on a Top‐MoSe₂/GeSe/Bottom‐MoSe₂ (T‐MoSe₂/GeSe/B‐MoSe₂) van der Waals dual‐heterojunction is proposed. Benefitting from the effective separation and shortening transmission distance of photocarriers by fully depleted Van der Waals dual‐heterojunction on both sides of in‐plane anisotropy of GeSe, the anisotropic photocurrent ratio (I_max/I_min) of T‐MoSe₂/GeSe/B‐MoSe₂ photodetector can reach as high as 12.5 (635 nm, 0 V). This value is 3.5‐fold higher than that of MoSe₂/GeSe photodetector, and 7‐fold higher than that of the pristine GeSe photodetector in this work. The responsivity of the T‐MoSe₂/GeSe/B‐MoSe₂ photodetector (206 mA W⁻¹, 0 V) is 5 times higher than that of the MoSe₂/GeSe photodetector. In addition, the T‐MoSe₂/GeSe/B‐MoSe₂ photodetector exhibited a high light on/off ratio of 4 × 10⁴ at 0 V. This work provides novel insights for developing high‐performance polarization‐sensitive imaging photodetectors.