Self‐Driven Ultrafast Response Photodetector Based on Graphene/Water/Silicon Structure

The graphene/water/semiconductor structure can convert kinetic energy into direct current output using the polarization principle, showing its unique physical characteristics and superior performance in the power generation direction. Herein, a photodetector application is developed based on the structure and reveals the physical mechanism of the displacement current caused by the polarization of more water molecules induced by silicon upon excitation under illumination. Furthermore, the research uses a graphene/water/silicon heterojunction as a self‐driven photodetector with a wide response band contains from ultraviolet to visible light, the photodetector has a high sensitivity to the incident light of 635 nm with a responsivity of 433.46 mA W −1 and detectivity as 1.57 × 10 12 Jones. Moreover, the photodetector based on graphene–water–Si has an ultrafast response speed, with a typical rise/fall time of 564/766 ns. The photodetector remains substantial stable while sealed with polymethyl methacrylate after storage in air for 1 month. These results imply that graphene/water/silicon heterojunctions may have great potential for practical applications as high‐performance self‐driven photodetectors.