Control of the Cu2O crystal orientation and the application of a ZnO/Cu2O self-powered photodetector in visible-light-encrypted communication

Reducing carrier trapping in the grain boundary of semiconductor materials can improve the carrier transport. Adding Na2EDTA in the electrolyte can regulate the growth process of Cu2O thin films electrochemically deposited at low temperature, improve the crystal quality, and transform from the polycrystalline structure into a single-crystal-like structure oriented along the (111) crystal plane. As a result, the interface transfer resistance of ZnO/Cu2O heterostructure devices is reduced, the photogenerated carrier transport ability is improved, and the self-powered photoresponse properties of heterostructure devices are improved. Based on the dual-band photoresponse characteristics of ZnO/Cu2O, a device without bias voltage was applied in the “OR” gate of a UV and visible dual-band light controlling digital logic circuit. The encrypted optical signal was realized and the security of visible light communication was improved by the encoded UV and visible dual-band light.