Carbazole dyes with different lengths of alkyl group on oligothiophene were newly synthesized to study the influence of the chain length on photovoltaic performance of dye-sensitized solar cells. It was found that the amount of adsorbed dyes increased with the decrease of the alkyl chain length, while the charge recombination rate was comparable between the dyes with n-propyl and n-hexyl chains but prompt with dodecyl chains.