Pore Size Distribution and Porosities of Nano-TiO2 Films Made by Using Cellulosic Thickener and Their Influence on Performance of Dye-Sensitized Solar Cells

A series of mesoporous TiO2 films with different average pore sizes and distributions were prepared by changing the addition content of cellulosic thickener in the pastes. The BET surface area shows that, for the samples with 3, 5, 10 and 15 wt % cellulosic thickener, the average pore size remained centered at 14-15 nm, but the pore size distribution became narrower with the increase of cellulosic thickener addition. With further increase of cellulosic thickener to 21 and 30 wt %, the average pore size decreases to 13 and 11 nm, and the pore size distribution also became much narrower. The sample, prepared from the paste with 15 wt % cellulosic thickener, shows the best result: short-circuit photocurrent density 13 mA/cm^2, open-circuit photovoltage 0.72 V, fill factor 0.68, and conversion efficiency 6.4%.