Design of dye-sensitized solar cells using TiO2 pastes with different secondary particles sizes

Titanium dioxide (TiO2) pastes containing secondary particle with varying sizes are prepared by modulating the dispersion time of the dispersion liquid. The appearances, mesoscopic structures, and transmission spectra of the TiO2 layers constructed using these pastes depend on the sizes of the secondary particles. However, the dye-sensitized solar cells (DSSCs) constructed using different pastes show similar photoelectric conversion performances despite the different mesoscopic structures and transmission properties of the TiO2 layers. The DSSCs based on the experimental TiO2 pastes show lower photoelectric conversion efficiencies compared with the DSSC constructed using a commercially available reference paste. These results suggest that the primary TiO2 particles have a greater influence on the photoelectric conversion performance of the DSSC than the secondary particles. The incident photon-to-current conversion efficiency spectra of the DSSCs based on the TiO2 pastes exhibit a slight dependence on wavelength. Thus, it is possible that minor light-scattering effects resulting from the mesoscopic structure of TiO2 occur in the DSSCs constructed using the pastes. These results indicate that TiO2 pastes with fixed primary particle sizes but different secondary particle sizes can be used to change the appearance or design of DSSCs without affecting their photoelectric conversion performance.