Responsivity to solar irradiation and the response time of photodetectors that use ZnO nanoparticles with and without thermal annealing in pure oxygen ambient

The optoelectronic properties of photodetectors that use ZnO nanoparticles under illumination by sunlight are determined. To investigate the role of the oxygen-vacancy (VO) concentration in ZnO nanoparticles on the responsivity to solar irradiation and its influence on the response time of devices that use ZnO nanoparticles, ZnO nanoparticles were annealed at 800 °C in pure oxygen ambient for 30 min. Thermal annealing leads to the improvement of the ZnO stoichiometry, increasing the crystallite size. A direct link between the responsivity to solar irradiation, the response time and the VO concentration is established. The experimental results show the important of controlling the VO concentration to optimize the solar-irradiation detectors that use ZnO nanoparticles.