N719-dye sensitized amorphous zinc oxide films for NO2 detection under visible-light illumination

In this paper, a room-temperature NO₂ gas sensor has been developed based on dye sensitized amorphous ZnO (a-ZnO) film. The dye sensitized a-ZnO sensor shows a remarkable reduction of base resistance under visible light illumination. The sensor resistance is firstly reduced by the photogenerated electrons transferred from the dye to the a-ZnO, and then reduced by desorption of oxygen on a-ZnO surface under light illumination. The dye sensitized sensors show significant responses to low concentration NO₂ and the sensor response increases linearly with the NO₂ concentration. The use of dye makes the a-ZnO sensors have significant responses to NO₂ at room temperature under visible light illumination, which paves a new way to develop room temperature gas sensors based on wide-gap semiconductors.