In recent times, Mn doped quantum dot sensitized solar cells (QDSSCs) have shown a lot of interest as it provides a different strategy to improve the photovoltaic performances. In this work, we have systematically studied the effect of Mn2+ dopant concentration on the photovoltaic performances of CdS based QDSSCs. The open circuit potential increases systematically with increase in Mn2+ dopant concentration. The efficiency of the solar cell increases from 1.63% to 2.53% from undoped to 7.5% doped CdS. The role of Mn2+ in enhancing the photovoltaic performances was further probed by open circuit voltage decay and the energy levels were studied using transient absorption spectroscopy. Both spin and orbital forbidden Mn d-d transition (T-4(1) - (6)A(1)) helps in reducing the recombination inside the solar cell, which improves the overall photovoltaic performances. (C) 2014 Elsevier Ltd. All rights reserved.