Effects of Particle Size on Properties of TiO2 Nanoparticle Thin Films Deposited by Electrophoresis

The absence of cracks and a high optical transparency are critical factors for obtaining high performance when TiO2 thin films are used as cathodes in dye-sensitized solar cells (DSSCs). Synthesized and classified TiO2 nanoparticles were deposited by constant-current electrophoresis in ethanol. The optical transparency of thin films and the DSSC efficiency increased rapidly with decreasing particle size and increasing film homogeneity. This increase in the DSSC efficiency suggests that the electron conduction path in a thin film consists of connections in the crystal lattice formed between TiO2 nanoparticles. This formation of connections increases the electron diffusion length.