Swift uptake of Ru dyes and improvement of photovoltaic performances for dye-sensitized solar cells (DSC) are reported. Ru dyes such as black dye [(C4H9)(4)N](3)[Ru(Htcterpy)(NCS)(3)] (tcterpy = 4,4',4''-tricarboxy-2,2':6',2''-terpyridine) and N3 dye [cis-di(thiocyanato)-N,N'-bis(2,2'-bipyridyl-4,4'-dicarboxylato) ruthenium (II)] are adsorbed on nano-porous TiO2 layers under a pressurized CO2 atmosphere to bond Ru dyes on inner surfaces of TiO2 in nano-porous layers effectively. The time needed for N3 dye adsorption under a pressurized CO2 condition is drastically shortened to 30 min from 300 min needed for a dipping process. The amount of N3 dye molecules increases from 15 to 20 nmol/cm(2)/mu m when N3 dye is adsorbed under a pressurized CO2 atmosphere. The pressurized CO2 process increases short circuit current, fill factor, and open circuit voltage which are associated with better coverage of TiO2 surfaces with dye molecules. They decrease surface traps of porous TiO2 layers. This retards back electron transfers from TiO2 layers to iodine in electrolytes and facilitates electron diffusion in TiO2 layer. Measurement of the electron lifetime and electron diffusion coefficient in the cells supports the mechanism. (c) 2006 The Electrochemical Society.