Optimization of Cu(In,Ga)Se2 Solar Cell and its Comparative Performance Analysis for Employing Different Buffer and Window Layers Through Numerical Simulation and Analysis Using SCAPS-1D

In this research, a numerical simulation and analysis of the second generation thin film solar cell Copper Indium Gallium diselenide Cu(In,Ga)Se₂ is conducted in order to optimize its performance and compare among the cells using different material for buffer and window layer. The one-dimensional solar cell simulation program SCAPS-1D (Solar Cell Capacitance Simulator), originally developed for polycrystalline solar cells and accommodating thin film structures, is used for the simulation and analysis purpose. Of the different thin-film based solar cells, the most promising chalcopyrite compound, copper indium gallium diselenide (CIGS) solar cell, has now a laboratory research cell efficiency of 22.6% close to 25.7% of conventional Crystalline Silicon (C-Si) solar cell. Though it presently lags the cadmium telluride (CdTe) compound (15.7% compared to 18.6% for CdTe solar cells) and the C-Si solar cell (24.4% solar module efficiency) in terms of solar module efficiency, its theoretical efficiency limit of 33.5% surpasses others. The chalcopyrite compound CIGS outperforms its kesterite counterpart by a huge difference (22.6% compared to 12.6%) in terms of laboratory research efficiency and is pushing the limit at a faster rate so as to exceed that of the conventional C-Si solar cell in near future most probably. The SCAPS-1D, compared to other simulation programs, facilitates the highest number of DC and AC electrical measurements under dark and light conditions. The effects of variation of thickness, bandgap and concentration of the p-type Cu(In,Ga)Se₂ (CIGS) absorber layers on the efficiency of CIGS solar cell are investigated. The change in CIGS solar cell efficiency with change in temperature is studied, too. Two different buffer layers namely CdS and In₂S₃ are considered for the simulation of the CIGS solar cell. The thickness of the buffer layer, its bandgap and concentration are taken into consideration for optimization. As for the window layer, ZnO and SnO₂ are employed for the numerical simulation. The thickness of the window layer is varied and its effect on the efficiency of the solar cell is investigated. The open-circuit voltage, short-circuit current density, fill factor and quantum efficiency of the CIGS solar cell are observed from the SCAPS simulation besides the solar cell efficiency. The aim of the work is to optimize the efficiency of the Cu(In,Ga)Se₂ (CIGS) solar cell through the optimization of the deposition conditions for the absorber layer, buffer layer and window layer. A comparison among different CIGS cell structures employing different buffer layers and window layers is also performed in terms of efficiency and other essential parameters as mentioned-above.