The effects of the thickness of TiO2 films on the performance of dye-sensitized solar cells

Nanocrystalline anatase TiO2 thin films with different thicknesses (0.5–2.0 μm) have been deposited on ITO-coated glass substrates by a sol–gel method and rapid thermal annealing for application as the work electrode for dye-sensitized solar cells (DSSC). From the results, the increases in thickness of TiO2 films can increase adsorption of the N3 dye through TiO2 layers to improve the short-circuit photocurrent (Jsc) and open-circuit voltage (Voc), respectively. However, the Jsc and Voc of DSSC with a TiO2 film thickness of 2.0 μm (8.5 mA/cm2 and 0.61 V) are smaller than those of DSSC with a TiO2 film thickness of 1.5 μm (9.2 mA/cm2 and 0.62 V). It could be due to the fact that the increased thickness of TiO2 thin films also resulted in a decrease in the transmittance of TiO2 thin films thus reducing the incident light intensity on the N3 dye. An optimum power conversion efficiency (η) of 2.9% was obtained in a DSSC with the TiO2 film thickness of 1.5 μm.