This work investigates the improvement in efficiency of quantum dot sensitized solar cells (QDSSCs) using CuS/PbS as counter electrode, which results in formation of highly efficient counter electrode for liquid-junction QDSSCs. The QDSSC on based CuS/PbS counter electrode exhibits power conversion efficiency (eta) of 2.2%, which is higher than that of CuS counter electrode, 1.17%. The improvement in h is probably attributed to the reduction of electron back into CuS/PbS counter electrode. Electrochemical impedance spectroscopy and cyclic voltammetry results confirm that higher value of eta in CuS/PbS counter electrode is because of this novel counter electrode which shows superior photo-electrochemical performance and electro-catalytic properties. Another reason for this higher eta might be the reduction in the charge transfer resistance at the counter electrode/electrolyte interfaces. (C) 2014 Elsevier Ltd. All rights reserved.