Size-Distribution Effects of TiO₂ Nanopowders Synthesized by Chemical Vapor Condensation Method for Dye-Sensitized Solar Cells

The size distribution effects of TiO₂ nanoparticles synthesized by chemical vapor condensation (CVC) have been investigated. Nanoparticles of sizes 3–5 nm, 10–400 nm and 30–400 nm were synthesized at synthesis pressures of 5 kPa, 40 kPa and 100 kPa, respectively. Anodes of the dye-sensitized solar cell (DSSC), when doped with 3–5 nm nanoparticle (synthesized at 5 kPa) exhibited the highest photoconversion efficiency (5.04%), which is attributed to (1) narrow size-distribution of nanoparticle and pore, (2) high specific surface area and (3) high transmission of the dye absorption wavelength. However, anodes fabricated with 10–400 nm TiO₂ nanoparticles (synthesized at 40 kPa) produced the lowest photo-current. This could be due to sintering of bi-size nanoparticle, because the bi-size of nanoparticles produced the smaller pore size and lower concentration of pore volume during sintering and which results in the poor penetration of electrolyte into the porous TiO₂.