UV and visible light controllable depletion zone of ZnO-polyaniline p-n junction and its application in a photoresponsive sensor.

In this communication, we report that the depletion zone thickness of the p-n junction between an n-type ZnO and a p-type polyaniline could be controlled by UV and visible light illumination. Based on this princile, photoresponsive sensors were constructed by combining polyaniline thin film and ZnO nanorods. Different from pure ZnO nanomaterials whose conductivity increases when they are exposed to UV illumination, the conductivity of the photoresponsive sensor studied in this communication decreased when the UV light was turned on. The surface modification of ZnO could switch the wavelength of the response light from UV to visible light.