Dysprosium doping in CdTe@CdS type II core/shell and cosensitizing with CdSe for photocurrent and efficiency enhancement in quantum dot sensitized solar cells

Quantum dot sensitized solar cells (QDSSCs) based on the II-VI QDs have become a promising and attractive technology due to their unique properties. However, the applications of the II-VI QDs, especially CdTe QDs, have still been restricted. Herein, a CdTe@Dy-doped CdS core/shell QDs cosensitized with CdSe QDs have been developed as a sensitizer in QDSSCs for enhancing the light-harvesting range and efficiency, accelerating charge separation, and suppressing charge recombination. The fabricated QDSSCs using TiO2/CdTe@Dy-doped-CdS/ CdSe/ZnS photoanode exhibited the best short-circuit current (JSC = 20.08 mA/cm2) and power conversion efficiency (n=8.26%) in comparison with that of other photoanodes comprising TiO2/CdTe, TiO2/CdTe@CdS, TiO2/CdTe@CdS/ZnS, TiO2/CdTe@CdS/CdSe/ZnS, and TiO2/CdTe@CdS/CdSe/Dy-Doped ZnS. As the obtained results from Diffuse Reflectance Spectroscopy, Photoluminescence, and Electrochemical Impedance Spectroscopy revealed, the CdTe/CdS type-II core/shell structure QDs leads to a wide absorption range, fast electron injection, and slower recombination rate because of the spatially indirect energy gap formation. Moreover, the presence of