Performance Optimization of CIGS Thin Film Solar Cell Using SCAPS

Introduction: Solar energy represents a highly promising renewable energy source in India, supported by favorable climatic conditions and national initiatives such as the National Solar Mission. The objective of this study is to enhance the energy conversion efficiency of CIGS thin-film solar cells by systematically optimizing key absorber layer parameters and developing an environmentally benign, cadmium-free device architecture. Methods: A standard CIGS/CdS/ZnO reference cell was first established, followed by the development of a calibrated and correlated numerical model using SCAPS-1D. The effects of absorber bandgap, acceptor doping concentration, and thickness on device performance were investigated over the ranges of 1.040–1.411 eV, 1015–1017 (/cm3), and 0.5–2 μm, respectively. Multiple simulation iterations were performed to identify the optimal absorber parameters. Additionally, toxic CdS was replaced with ZnS, and various buffer layer compositions were evaluated. Results: The optimized CIGS/ZnS/ZnO solar cell with absorber bandgap of 1.268eV, acceptor doping concentration of 1015(/cm3), and thickness of 1.50μm achieved a conversion efficiency of 26.82%, which is 29.12% higher than the reference cell ‘A’(20.77%). Discussion: The observed efficiency enhancement is attributed to improved optical absorption, carrier transport, and reduced recombination losses achieved through systematic absorber optimization and the use of a wide-bandgap ZnS buffer layer. The cadmium-free configuration also reduces parasitic absorption at short wavelengths, leading to improved current density. Conclusion: This study demonstrates that systematic optimization of absorber layer parameters combined with the successful implementation of a cadmium-free ZnS buffer can significantly enhance the performance of CIGS thin-film solar cells. The proposed CIGS/ZnS/ZnO architecture offers a high-efficiency, environmentally friendly alternative for next-generation photovoltaic devices.