In this paper, the pre-synthesized monodisperse PbS quantum dots were assembled on TiO2 films through direct adsorption. In consideration of the easy reaction between Pb-rich surface of PbS QDs and dissociative S2- of polysulfide electrolyte, a relatively mild post-treatment was selected to produce a CdS capping layer by chemical bath deposition route using thiourea as the sources of sulfur. Vis-NIR absorption spectra was adopted to confirm the change of the size and size distribution of the absorbed PbS QDs. Finally, the optimized treatment led to a stable panchromatic solar cell with 2.67% conversion efficiency and short circuit photocurrent density of 15.14 mA cm(-2). (C) 2014 Published by Elsevier Ltd.