Effect of dye concentration on electron injection efficiency in nanocrystalline TiO2 films sensitized with N719 dye

► Electron injection efficiency N719/TiO2 could be evaluated quantitatively. ► Injected electrons can be detected by time-resolved microwave conductivity measurements. ► The efficiency of electron injection is not affected by dye concentration on the surface. ► No dye aggregation occurs judged from adsorption isotherm and absorption spectra.