Preparation of Low-Defect Aluminum-Doped Zinc Oxide Nanostructure-Based Compact Layer by Vacuum Ultraviolet Irradiation for Quantum Dot-Sensitized Solar Cells

Al-doped ZnO (AZO) nanostructure-based compact thin films were successfully prepared via the irradiation of the precursor films containing zinc nitrate and aluminum nitrate under vacuum ultraviolet (VUV) radiation at 172 nm. The VUV irradiation can generate hydroxyl free radicals to make up for the oxygen defects on the as-prepared AZO thin films. Meanwhile, the photoactivation effect triggered by VUV irradiation can desorb the amorphous oxygen species adsorbed on the surface, thus significantly reducing the number of surface defects. By changing the ratio of aluminum nitrate to zinc nitrate, the doped amount of Al can be rationally adjusted for the promotion of electron mobility and conductivity. When the Al loading is 3%, the resultant AZO thin film has the highest electron mobility and conductivity. When used as a base compact layer in CdS/PbS quantum dot-sensitized solar cells (QDSSCs), the nanostructure-based AZO thin film could suppress the recombination of the photogenerated electrons and holes between the TiO2 mesoporous layer and FTO conductive glass. As a result, the assembled QDSSC based on the AZO thin film achieved a photoelectric conversion efficiency of 4.97%, higher than that based on the traditional AZO compact layer prepared by sintering at 450 °C (3.70%). Therefore, VUV irradiation is a promising strategy for the preparation of nanostructure-based compact thin films doped by metal oxides under low temperatures.