Visible-light photoelectrochemical photodetector based on In-rich InGaN/Cu2O core-shell nanowire p–n junctions

n-InGaN/p-Cu2O core-shell nanowire (NW) p–n junctions enable efficient self-powered photoelectrochemical photodetectors (PEC PDs) in the visible. The photocurrent density under one-sun illumination is enhanced by 8 times compared to that of bare InGaN NW PEC PDs due to maximized photocarrier separation in the built-in electric field of the p–n junction. The responsivity reaches 173 μA/W under one-sun illumination. The response times of 30–40 ms are among the shortest achieved for PEC PDs. Together with the long-time stability and reusability, a robust, easy to fabricate, and easy to operate self-powered PEC PD is introduced.