Dependence of electron transport in nanocrystalline TiO2 films sensitized with [NBu4]2[Ru(Htcterpy)(NCS)3]([NBu4]+ =tetrabutylammonium cation; H3tcterpy=4,4',4''-tricarboxy-2,4:2',4':2''-terpyridine) on the properties of TiO2 nanoparticles

Abstract Nanocrystalline TiO 2 colloids were prepared by hydrothermalization. The porosity and the size distribution of the particles increase with a longer hydrothermalization reaction period. The particle size decreases with lower reaction temperature. Electron transport in nanocrystalline TiO 2 film electrodes sensitized with [NBu 4 ] 2 [Ru(Htcterpy)(NCS) 3 ] ([NBu 4 ] +  = tetrabutylammonium cation; H 3 tcterpy = 4,4′,4″-tricarboxy-2,4:2′,4′:2″-terpyridine) (black dye) was investigated from the standpoint of TiO 2 particle properties such as particle size, size distribution, and porosity. When the size distribution and the porosity were comparable, the electron lifetime ( τ rec ) increased and the electron diffusion coefficient ( D ) decreased at smaller particle sizes. The value of D decreased when the porosity increased. Large differences in the diffusion length ( L = D τ rec ) among the TiO 2 films were observed. However, J sc did not depend on L . Thus, we conclude that the J sc values were more effectively influenced by the absorption coefficient ( α ) than by L .