Evaluation of TiO2 Nanoparticle Thin Films Prepared by Electrophoresis Deposition

The absence of cracks and a high optical transparency are critical factors for obtaining high performance when TiO2 thin films are used as the cathode material in dye-sensitized solar cells (DSCs). Synthesized and classified TiO2 nanoparticles were deposited by constant-current electrophoresis in various dispersion media. TiO2 nanoparticle thin films deposited using ethanol as the dispersion medium did not exhibit any apparent cracks and had a high optical transparency. The optical transparency of thin films and the DSC efficiency increased rapidly with decreasing particle size and increasing film homogeneity. The increase in the DSC efficiency suggests that the electron conduction path in the thin film consists of connections in the crystal lattice formed between TiO2 nanoparticles by the oriented attachment mechanism. This formation of connections increases the electron diffusion length.