Novel ZnO-Based Film with Double Light-Scattering Layers as Photoelectrodes for Enhanced Efficiency in Dye-Sensitized Solar Cells

A novel double light-scattering-layer ZnO (DL-ZnO) film consisting of ZnO monodisperse aggregates (MA-ZnO) as underlayer and sub-micrometer-sized platelike ZnO (SP-ZnO) as overlayer was fabricated and studied as dye-sensitized solar-cell photoanodes. It was found that DL-ZnO could significantly improve the efficiency of dye-sensitized solar cells (DSSCs) owing to its relatively high surface area and enhanced light-scattering capability. The overall energy-conversion efficiency (η) of 3.44% was achieved by the formation of DL-ZnO film, which is 47% higher than that formed by MA-ZnO alone and far larger than that formed by SP-ZnO alone (η = 0.81%). Furthermore, the η decay measurements for DL-ZnO cell showed that no significant decrease of η occurred even when DL-ZnO cell was placed for 100 h at ambient temperature. The charge recombination behavior of cells was investigated by electrochemical impedance spectra (EIS), and the results showed that among MA-ZnO, SP-ZnO, and DL-ZnO based cells, DL-ZnO based cel...