More than 5.0 g luminescent CdS quantum dots (QDs) were synthesized via a hot-bubbling route. The synthetic parameters including temperature, growth time, feeding ratio Cd/S and capping ligands were studied to show great influence on the optical properties. Two types of CdS "magic-sized" clusters (MSCs) emitting at 313 nm and 323 nm were obtained at temperature lower than 80 degrees C. The PL quantum yields of the CdS QDs reaches 11.6% when trioctyphosphine oxide was used as ligand. The prepared CdS QDs have been transferred into aqueous solution via ligand exchange (LE). To expand the spectral response in photovoltaic devices, two different sizes of CdS QDs were deposited on mesoporous TiO2/SiO2 electrode, and the co-sensitized solar cells (SCs) were prepared. It was found that the co-sensitized SCs show a higher conversion efficiency (eta = 1.55%) than the single sized QDs sensitized SCs (eta = 0.53%). The incident photon-to-current conversion efficiency (IPCE) of co-sensitized SCs showed two peaks at 370 nm and 460 nm which resembles the absorption peaks of the two different sized QDs. (C) 2013 Elsevier B.V. All rights reserved.