Flexible Cu2O/Cu film self-powered photodetector for high visible light selection and fast response

Spectral selection is one of the key performance parameters for visible light photodetectors (VLPD). However, as the absorbing layer of the VLPD, the semiconductor has strong ultraviolet light absorption, leading to poor visible light selectivity of the VLPD. This work fabricated a flexible photovoltaic VLPD based on Cu2O/Cu Schottky junction by annealing Cu foil. Under zero bias, the Cu2O/Cu VLPD showed the responsivity of 14 mA/W, the response time of 1 ms, and the detectivity of 8.8 x 1011 Jones to 620 nm light. Moreover, the detection band of the device is in the range of 500-640 nm, indicating excellent visible light selectivity. Optical and electrical characterization shows that the high visible selectivity of the device is mainly attributed to the fact that the penetration depth of visible light in Cu2O film matches the position of the Cu2O/Cu Schottky junction. This, in turn, induces the effective separation of the photogenerated carriers excited by the visible light. In addition, the bend detection performance of the device is demonstrated. This work provides a reference for improving the spectral selectivity of visible photodetectors.