Self-powered UV–visible photodetectors based on ZnO/Cu2O nanowire/electrolyte heterojunctions

• ZnO/Cu2O branched heterojunction arrays (BHAs) were synthesized.
• The BHAs were used in PEC type self-powered UV–visible photodetectors.
• They exhibited high responsivity of 19.3 mA/W for UV light.
• They also had high responsivity of 8.2 mA/W for visible light.

ZnO/Cu2O branched heterojunction arrays (BHAs) were synthesized via hydrothermal and chemical bath deposition process for the application in photoelectrochemical type self-powered UV–visible photodetectors. At zero bias, the photodetectors based on the ZnO/Cu2O nanowire/electrolyte heterojunctions exhibited high responsivities of 19.3 mA W−1 and 8.2 mA W−1 for UV and visible light, respectively, with a rise time of 0.14 s and a decay time of 0.36 s. The spectral response measurements carried out on the self-powered photodetectors based on ZnO/Cu2O BHAs demonstrate a significant increase of responsivity in the visible region compared to ZnO nanowire arrays (NWAs). The excellent photodetecting performance, low cost, non-toxic, and facile fabrication process make the photoelectrochemical type self-powered photodetectors based on metal oxide semiconductors promising candidates for next-generation UV–visible photosensing applications.