Optimization of Performance in Thin-Film CIGS Solar Cells: Silvaco Simulation of Doping and Absorber Layer Thickness

This study investigates the effects of doping concentration and absorber layer thickness on the performance of Cu(In,Ga)Se2 (CIGS) thin-film solar cells using detailed numerical simulations. The work focuses on identifying optimal design parameters to maximize power conversion efficiency by analyzing their influence on key device characteristics, including short-circuit current density, open-circuit voltage, and fill factor. The results indicate that the doping concentration critically impacts carrier transport and recombination dynamics. An optimal doping level of 6×10<sup>16</sup> cm<sup>-3</sup> enhances charge carrier collection, leading to simultaneous improvements in short-circuit current density, open-circuit voltage, and fill factor. Doping beyond this value increases series and shunt resistances, which reduces the efficiency gains, emphasizing the importance of precise doping control. The absorber layer thickness also plays a significant role in device performance. Increasing the thickness from 0.1 µm to 1 µm substantially improves photon absorption and carrier generation, resulting in a marked enhancement in efficiency. However, further increasing the thickness above 1 µm yields only marginal efficiency gains, as photon absorption reaches saturation and the recombination rate increases, highlighting the trade-off between absorption depth and minority carrier lifetime. Overall, the study demonstrates that careful optimization of both doping and absorber thickness is essential to achieving high-efficiency CIGS solar cells. Specifically, a doping concentration of 6×1016 cm<sup>-3</sup> combined with an absorber thickness in the range of 0.1-1 µm provides the most favorable conditions for device performance. These findings offer practical guidelines for experimental fabrication and numerical optimization, contributing to the design of more efficient thin-film photovoltaic devices. The insights provided by this work can guide future research in enhancing the performance of CIGS solar cells and other related thin-film technologies.