In this paper, we have succeeded in preparing the Quantum dots Solar cells with the high efficiency of 4.22% based on Cu2+ ions doped on CdSe Quantum dots by Successive ionic layer absorption and reaction. There are significant effects of Cu2+ ions on optical, physical, chemical and photovoltaic features of QDSSCs. As a result, the current density of the QDSSCs increased dramatically from 12 mA/cm2 for pure CdSe QDs to 19.915 mA/cm2 for Cu2+ ions doped on pure CdSe QDs. In fact, Cu2+ dopant rise in the conduction band of pure CdSe QDs, reduces recombination, enhances the efficiency of high harvesting, improve the charge transfer and collection. In addition, Cu2+ dopant raise the level of the conduction band of pure CdSe QDs, which leads to reduce the charge recombination, enhance the light-harvesting efficiency and improve the charge diffusion and collection. In the same way, we also illustrated photoluminescence decay to determine the lifetime of excited electrons and Electrochemical Impedance Spectra to calculate dynamic resistances in QDSSCs and explain the obtained results.