Effect of RF power level on the arc-TiO2 dense film for dye-sensitized solar cell performance

Graded index TiO₂ compact layer (arc-TiO₂) that improved transmittance and reduced electron recombination in dye-sensitized solar cell (DSSC) is employed by RF sputtering. Effects of arc-TiO₂ prepared at various RF sputtering power to the performances of DSSC were investigated by means of open-circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS). The slow decay behaviour of the photo-voltage attributed to the desirable merits of the arc-TiO₂ compact layer has been evidence by the OCVD measurement. The improvement of adhesion between arc-TiO₂ film and porous-TiO₂ has decrease the interfacial-charge resistance R1 in the EIS measurement, thus facilitating the charge-transfer process of the electron in the DSSC. A remarkable improvement in the overall conversion efficiency has been achieved at 100 W of RF power, representing almost 42 % increment compared to the cell without the compact layer is mainly due to the higher and red-shifted transmittance peaks, and also the ability to reduce the charge recombination in the DSSC.