We report a DFT/TDDFT computational investigation on dye-sensitized solar cells sensitized by two prototype perylene dyes. These widely investigated systems represent valuable models of dyes in which the different dye anchoring group gives rise to distinctively different time-resolved spectroscopic properties. By performing extensive TDDFT calculations on the dyes adsorbed onto a TiO2 nanoparticle model, we provide clear insight into the different excited state pattern exhibited by the two dyes, which therefore involve a different electron injection mechanism. The implications of such observation for dye-sensitized solar cells performance are also discussed. (C) 2010 Elsevier B. V. All rights reserved.