Enhancing the efficiency of Cu2Te thin-film solar cell with WS2 buffer layer: A simulation study

In this work, the Cd-free tungsten disulfide (WS2) material as the buffer layer is proposed in the copper telluride (Cu2Te)-based heterojunction solar structure. The Cu2Te thin-film photovoltaic organization of Ni/Cu2Te/CdS or WS2/SnO2:F(FTO)/Al has been designed and evaluated numerically by using the One Dimensional Solar Cell Capacitance Simulator. The WS2 buffer layer provides a significant improvement in the output parameters of the Cu2Te solar device compared to the cell with the CdS buffer. A high efficiency of 24.23% with Voc of 0.68 V, Jsc of 42.95 mA/cm2, and FF of 82.77% is obtained for the designed Cu2Te-based solar cell with WS2 buffer. The 'spike -like' band structure formed at Cu2Te/WS2 interface plays an important function in the enhancement of the outputs by minimizing carrier recombination. The thicknesses of 0.05 mu m for buffer and 1.0 mu m for absorber are optimized by considering the low fabrication cost. Moreover, the photovoltaic parameters of the Cu2Te solar cell are evaluated by varying the doping concentration, bulk and interface defects, operative temperature, rear contact work function, and cell resistances. The data outcomes imply that the anticipated Cu2Te-based photo-voltaic device with a non-toxic WS2 buffer can be an efficient substitute to the toxic CdS for cost-effective and stable thin-film solar devices.