Formation of Silica Nanolayers on ZnO Electrodes in Dye‐Sensitized Solar Cells

Abstract

AbstractZinc oxide electrodes for use in dye‐sensitized solar cells were coated with thin silica layers by using a sol–gel transformation of tetraethylorthosilicate (TEOS). Coating solutions were prepared by mixing TEOS and diluted ammonia while stirring and ultrasonificating simultaneously. Two kinds of coating methods (immersing and dip‐coating) were adopted and compared to control the thickness of the silica layers on a nanometer scale. With the immersing method a relatively thick SiO2 coating was made on zinc oxide particles on the electrodes, which resulted in an increase in the open‐circuit photovoltage (Voc) and a large decrease in the short‐circuit photocurrent density (Jsc). In contrast, by using the dip‐coating method, with a relatively low withdrawal speed of 100 μm s–1, thinner SiO2 layers could be formed on the zinc oxide particles and a high Jsc as well as a high Voc was obtained. These results demonstrate that the Voc characteristics of solar cells using silica‐coated zinc oxide electrodes can be enhanced by controlling the structure of the silica‐coating layers.