Solar-irradiation photodetectors based on ZnO nanoparticles with gold and indium electrodes

The optoelectronic properties of the In/ZnO nanoparticles/In and Au/ZnO nanoparticles/Au devices under illumination by sunlight are determined. ZnO nanoparticles were prepared by the sol-gel method. It is shown that the value of photosensitivity for Au/ZnO nanoparticles/Au devices is larger than the value of photosensitivity for In/ZnO nanoparticles/In devices. This is because of the formation of the depletion region at the Au/ZnO interfaces. In order to understand the relationship between the visible-emission absorption and photosensitivity, sub-gap state generation is used to describe the mechanism for the sensitivity of ZnO nanoparticles to solar irradiation. A direct link between the sensitivity to solar irradiation, oxygen vacancies and the photo-response time is established.