Microwave heating to form porous TiO2 layer on high-haze FTO film for dye-sensitized solar cell

Abstract

A porous TiO2 layer was formed on a fluorine-doped tinoxide (FTO) film using a microwave heating technique, and applied to a dye-sensitized solar cell (DSSC). Under microwave irradiation, a self-heating process was induced in the FTO film to raise the substrate temperature up to 600 °C within a minute. After 12 min of microwave irradiation of the porous TiO2/FTO double layer, the internal resistances at the TiO2/FTO interface and the TiO2 interparticles were effectively reduced. By tuning the haze of the optical transmission through the FTO film, the photovoltaic performance was enhanced, and the conversion efficiency reached values as high as 7.2% at a haze of 31.5%, which was attributed to effective light harvesting within the cell. Unique ionic diffusion induced under microwave irradiation was detected at a lower substrate temperature, and the cell that formed at a substrate temperature of 350 °C exhibited a conversion efficiency of 6.5%, which is high for the sintering temperature. Although the photovoltaic performance was comparable to that of a general DSSC, a rapid sintering process that reduced the internal resistance within the cell was demonstrated using a microwave heating technique. Compared with a conventional electric furnace, the microwave heating technique can produce ceramics with high densities in a short time, and is an ideal tool for producing DSSCs.