Effect of substrate temperature on the facing target sputter deposited TiO2 photoelectrode of dye-sensitized solar cells

Abstract

Nanocrystalline TiO2 photoelectrodes were successfully deposited on SnO2:F coated glass substrate by facing target reactive sputtering technique with different substrate temperatures ranging from room temperature to 400°C. Low cost chlorophylline based dye was used along with carbon paste on SnO2:F glass as a counterelectrode. All the TiO2 electrodes show good crystallinity. It has been observed that increase of substrate temperature not only alters the ratio of anatase and rutile phase but it also markedly changes the crystal orientation. The amount of dye incorporation was found to be highly dependent on the microstructure of electrodes, as apparent from optical measurements. The dye-sensitized solar cells, comprised of TiO2 photoelectrode, deposited at substrate temperature of 200°C, show maximum photoelectric conversion efficiency; however, further enhancement of sputtering temperature drastically reduces the efficiency. The variation of photoelectric conversion efficiency of the solar cells with TiO2 electrodes deposited at different substrate temperatures is discussed with the analysis of different microstructures of the TiO2 photoelectrodes and the corresponding dye incorporation. Moreover, all the dye-sensitized solar cells of this present investigation exhibit reasonably good fill factor value.