Preparation of ZnO compact layer using vacuum ultraviolet for dye-sensitized solar cells

Vacuum ultraviolet (VUV) light with a wavelength of 172 nm has the capacity to convert the oxygen contained metal organic precursor into metal oxide. Here, zinc acetate precursor thin film is directly converted into ZnO thin film by the irradiation of 172 nm VUV light rather than the high temperature sintering. The converting processes were demonstrated by the measurements of FTIR, XRD, SEM and XPS. And then the effect of irradiating time on the morphology, thickness and transparence of the prepared ZnO thin films was discussed. The ZnO thin film was further used as the compact layer in the photoelectrode of dye-sensitized solar cell (DSSC) to suppress the recombination processes of photogenerated electrons on the conducting glass electrode. For the different irradiation times, the photoelectric conversion efficiency of DSSC based on the compact layer prepared by the irradiation for 30 min is the highest reaching 10.27%, which is also higher than that of DSSCs without the compact layer and even with the compact layer prepared by the high temperature sintering. The uniform, dense, pinhole-free and amorphous ZnO thin film on the conducting glass substrate can be successfully prepared using the VUV irradiation technology for the compact layer of DSSCs.