Polarization‐Sensitive and Self‐Driven Pyro‐Phototronic Photodetectors Based on MoS₂‐Water Heterojunctions

Abstract Polarization‐sensitive and self‐driven pyroelectric‐based photodetectors have recently gained interest due to their potential application in artificial electronic eyes, biomedical imaging, and optical switches. Here, a photodetector based on light modulation‐induced polarization and depolarization of water molecules on the surface of a 2D MoS₂ crystal is reported. The MoS₂‐water heterostructure photodetector serves as a self‐driven pyro‐phototronic device that converts light‐induced thermal energy to electrical signals, leading to a transient photoresponsivity as high as 24.6 mA W⁻¹ and a specific detectivity of 2.85 × 10⁸ Jones under 470 nm wavelength at zero bias. Due to the formation of a built‐in electric field at the MoS₂‐water interface, this structure also has a high steady–state responsivity of 3.62 A W⁻¹ and detectivity of 9.18 × 10⁸ Jones at 3 V bias, along with a fast response time of ≈0.74 ms. Moreover, due to the rearrangement of the hydrogen bond network in the liquid water upon visible light illumination, the MoS₂‐water photodetector is light polarization‐sensitive. The simple fabrication process, low cost, polarization sensitivity, and high performance of the MoS₂‐water structure make it an excellent candidate for liquid‐compatible photodetectors.