Dye-Sensitised Solar Cells Based on Large-Pore Mesoporous TiO2 with Controllable Pore Diameters

Mesoporous TiO2 (meso-TiO2) is a promising photoelectrical nanomaterial for high dye-sensitised solar cell (DSSC) performance, because its nanochannels offer a large internal surface area to allow for more dye adsorption. The interconnected grains facilitate rapid electron transport both within the meso-TiO2 film and at the film electrode dye/redox shuttle electrolyte interfaces. In this work, a series of DSSCs has been fabricated on the basis of meso-TiO2 with large controllable pore sizes (6.5, 8.2 and 11.0 nm). It was found that the DSSC with the 8.2 nm meso-TiO2 photoelectrode has the highest photoelectrical conversion efficiency, which is higher than that of the conventional P25 nanoparticulate DSSC under the same conditions. The measurements of the N-2 sorption isotherms and the photovoltage transient demonstrates that such improved efficiency can be ascribed to the larger surface area and the fastest interfacial charge transfer. Meanwhile, the effect of different pore sizes on the photoelectrical conversion efficiency has been systematically investigated, and a possible model for the efficient electrolyte percolation in the dye-sensitised mesoporous photoelectrode has been proposed.