Two dimensional NbSe/NbO metal-semiconductor heterostructure-based photoelectrochemical photodetector with fast response and high flexibility.

Two dimensional (2D) metal-semiconductor heterostructures are promising for high-performance optoelectronic devices due to fast carrier separation and transportation. Considering the superior metallic characteristics accompanied by high electrical conductivity in NbSe, surface oxidation provides a facile way to form NbSe/NbO metal-semiconductor heterostructures. Herein, size-dependent NbSe/NbO nanosheets were achieved by a liquid phase exfoliation method and a gradient centrifugation strategy. These NbSe/NbO heterostructure-based photodetectors show high responsivity with 23.21 μA W, fast response time of millisecond magnitude, and wide band detection ability in the UV-Vis region. It is noticeable that the photocurrent density is sensitive to the surface oxygen layer due to the oxygen-sensitized photoconduction mechanism. The flexible testing of the NbSe/NbO heterostructure-based PEC-type photodetectors exhibits high photodetection performance even after bending and twisting. Beyond that, the solid-state PEC-type NbSe/NbO photodetector also achieves relatively stable photodetection and high stability. This work promotes the application of 2D NbSe/NbO metal-semiconductor heterostructures in flexible optoelectronic devices.