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 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 homeogenity. 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 orientated attachment mechanism. This formation of connections increases the electron diffusion length.
