The Study of Metal Sulfide as Efficient Counter Electrodes on the Performances of CdS/CdSe/ZnS-co-sensitized Hierarchical TiO(2) Sphere Quantum Dot Solar Cells

The effects of using different counter electrode metal sulfides on the performances of solar cells made with CdS/CdSe/ZnS quantum dots co-sensitized onto hierarchical TiO(2) spheres (HTSs) used as photo-electrode are reported. The HTS in the QDSSCs is composed of an assembly of numerous TiO(2) spheres made by the solvolthermal method. The photoelectrical performance of HTS/CdS/CdSe/ZnS coupled to CuS or to Cu(2)ZnSn(S(1 − x)Se(x))(4) with x = 0, 0.5, or 1.0 counter electrodes (CEs) were compared to those coupled to Pt CE. The HTS/CdS/CdSe/ZnS coupled to the CuS CE showed the highest power conversion efficiency η (of 3.46%). The efficiencies η of 1.88, 2.64, and 2.06% were obtained for CZTS (x = 0), CZTS(0.5)Se(0.5) (x = 0.5), and CZTSe (x = 1), respectively. These are significantly higher than those using a standard Pt CE (η = 0.37%). These higher efficiencies are the results of the higher electrocatalytic activities when the metal sulfide CEs are used.