Quantum dot sensitized solar cell based on the different photoelectrodes for the enhanced performance

Abstract

In this work, the TiO2 nanoparticles have been used for the fabrication of CdS/TiO2, CdSe/TiO2, ZnS/CdSe/CdS/TiO2, ZnS/CdSe:Cu/CdS/TiO2 and ZnS/CdSe:Mn/CdS/TiO2 quantum dot-sensitized solar cells. The TiO2 films are sensitized with consecutive layers of CdS, CdSe quantum dots. Further, Cu2+ or Mn2+ ions were doped on CdSe quantum dots by successive ion layer adsorption and reaction. The performance of the QDSSCs is examined in detail using polysulfide electrolyte with Cu2S counter electrode. The cells containing CdSe quantum dots doped with the these ions show an improved short circuit current density (∼20.01 mA/cm2) with a maximum power conversion efficiency of 4.31% under 1 sun illumination. This enhancement is mainly attributed due to the superior light harvesting ability of the CdSe:Cu or CdSe:Mn quantum dots and make large accumulation of photo-injected electrons in the conduction band of TiO2 nanoparticles. In addition, the combination of doped CdSe and the presence of CdS layers caused lower recombination of photo-injected electrons with the electrolyte. These changes are demonstrated in this studying by using photovoltaic and electrochemical impedance spectroscopy.