Boosting Photoresponse of Self-Powered InSe-Based Photoelectrochemical Photodetectors via Suppression of Interface Doping

Two-dimensional (2D) InSe is a good candidate for high-performance photodetectors due to its good light absorption and electrical transport properties. However, 2D InSe photodetectors usually endure a large driving voltage, and 2D InSe-based heterojunction photodetectors require complex fabrication processes. Here, we demonstrate high-performance self-powered InSe-based photoelectrochemical (PEC) photodetectors using electrochemical intercalated ultrathin InSe nanosheets. The ultrathin InSe nanosheets have good crystallinity with a uniform thickness of 1.4-2.1 nm, lateral size up to 18 μm, and yield of 82%. The self-powered InSe-based PEC photodetectors show broadband photoresponse ranging from 365 to 850 nm. The photoresponse of InSe-based PEC photodetectors is boosted by suppressing p-type doping of the intercalator with annealing, which improves the electrical properties and facilitates electron transport from InSe to the electrode. The self-powered annealed InSe (A-InSe) PEC photodetectors show a high responsivity of 10.14 mA/W and fast response speed of 2/37 ms. Moreover, the self-powered PEC photodetectors have good stability under UV-NIR irradiation. Furthermore, the photoresponse can be effectively tuned by the concentration and kind of electrolyte. The facile large-scale fabrication and good photoresponse demonstrate that 2D ultrathin InSe can be applied in high-performance optoelectronic devices.