Fast sensitization process of ZnO-nanorod-array electrodes by electrophoresis for dye-sensitized solar cells

A novel electrophoresis based dye adsorption technique is developed for the process of ZnO-nanorod-array dye-sensitized solar cells (DSSC). By applying a constant current electrophoresis procedure, ZnO electrodes were successfully sensitized by N719 dye, and the effects of varying the electrophoretic current and duration time on the performance of DSSC were investigated. It is found that abundant dye adsorption can be obtained within significantly reduced sensitization time by electrophoresis compared to standard immersion method. Thicker ZnO-nanorod-array film and lower electrophoretic current requires longer electrophoresis time to reach the optimal sensitization effect, while very long sensitization time will result in dye agglomeration, which is harmful to the performance of DSSC. The fast dye adsorption process is more advantageous as the ZnO-nanorod-array film becomes thicker because dye molecules can readily penetrate into the depth of ZnO film in a very short time, during which the formation of Zn2+/dye complex can be suppressed.