Photoinduced charge transfer process in p-Cu2O/n-Cu2O homojunction film and its photoelectric gas-sensing properties.

In this study, the p-Cu2O/n-Cu2O homojunction film was prepared by a simple two-step electrodeposition method. The photoinduced charge transfer process in p-Cu2O/n-Cu2O homojunction film was studied using surface photovoltage technique. Then, the p-Cu2O/n-Cu2O homojunction film was assembled into a photoelectric gas sensor for sensing acetaldehyde both under 405 nm and 532 nm light irradiation at room temperature. For 532 nm light irradiation, excess photoinduced electrons migrate to the irradiated n-Cu2O side affected by the interfacial built-in electric field and promote desorption of acetaldehyde, which results in a higher sensitivity than that under 405 nm light. Our results demonstrated that constructing junction structure in photoelectric gas-sensing materials is an effective approach to achieve high sensitivity at room temperature.