Thermal Science and Energy Engineering

Cadmium Telluride (CdTe) thin film solar cell has long been recognized as a leading photovoltaic candidate for its high efficiency and low cost. The efficiency of CdTe based solar cell can be increased using ternary material as window and absorber layer. In this study a new solar cell structure was proposed, where Zinc Cadmium Sulfide (ZnxCd1-xS) was used as window layer and Zinc Cadmium Telluride (ZxCd1-xTe) was used as an absorber layer with an added advantage of variable band gap. By varying the composition of the zinc content, the band gap was varied between 2.42-3.7eV for ZnCdS and 1.45-2.25eV for ZnCdTe respectively, thereby increasing the cell’s performance in the lower wavelength region, resulting in higher efficiency. In this work the band gap of ZnxCdx-1Te layer is used 1.53eV which is in the optimum range, can be achieved with Zn composition of 0.09. Incorporation of Zn can be reduced the window and absorber layer thickness significantly, which eventually will reduce the material cost, save processing time and energy required for fabrication. The numerical simulation has been performed using AMPS-1D simulator to explore the possibility of higher efficiency and stable ultra thin ZnCdS/ZnCdTe cell with suitable Back Surface Field (BSF). The performance parameters were found better in the modified cell structure. The effect of BSF layer and the operating temperature on the cell performance parameters was also investigated in this work. The cell structure of Glass/ZnO/Zn2SnO4/ZnCdS/ZnCdTe/ZnTe/Ni showed highest conversion efficiency of 21.17% than other cells with different BSF. The cell with Cu2Te BSF showed better stability with TC of - 0.15%/°C in the operating temperature range from 25˚C to 40˚C. After 40˚C temperature the cell with Cu2Te/Mo gives better stability as its efficiency remains almost unchanged in the operating temperature up to 100˚C with a TC 0.01%/˚C.