Two dimensional NbSe2/Nb2O5 metal–semiconductor heterostructure-based photoelectrochemical photodetector with fast response and high flexibility

Abstract

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 NbSe₂, surface oxidation provides a facile way to form NbSe₂/Nb₂O₅ metal-semiconductor heterostructures. Herein, size-dependent NbSe₂/Nb₂O₅ nanosheets were achieved by a liquid phase exfoliation method and a gradient centrifugation strategy. These NbSe₂/Nb₂O₅ heterostructure-based photodetectors show high responsivity with 23.21 μA W⁻¹, 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 NbSe₂/Nb₂O₅ heterostructure-based PEC-type photodetectors exhibits high photodetection performance even after bending and twisting. Beyond that, the solid-state PEC-type NbSe₂/Nb₂O₅ photodetector also achieves relatively stable photodetection and high stability. This work promotes the application of 2D NbSe₂/Nb₂O₅ metal-semiconductor heterostructures in flexible optoelectronic devices.