In-depth study of CIGS (Copper, Indium, Gallium, and Selenium) layer properties with the impact of silicon layer for enhancement of solar cell performance

• A CIGS-Si based solar cell achieving a PCE of 23.02 % is simulated using SCAPS-1D device simulator. • Alternating current analysis using complex impedance (Z*) and modulus (M*) for determining ionic transport and diffusion is presented. • The impact of incorporating Si layer on CIGS absorber layer on cell performance has been investigated thoroughly. • Impact of activation energy on charge transport is presented. • Relaxation times for ZnO/CdS, CdS/CIGS, and CIGS/Si interfaces are analyzed. Several studies using SCAPS-1D have been conducted to investigate the performance of solar cell devices, primarily focusing on J-V analysis for DC characterization. However, alternating current (AC) analysis using complex impedance functions (Z*) and modulus (M*) has revealed critical processes, such as ionic transport, recombination, and diffusion, which are essential for optimizing perovskite solar cell architectures. This approach allows for the determination of parameters like the time constant (τ i ) associated with each process. Here, we observe that ionic conductivity and electronic diffusion play key roles in balancing charge collection and recombination losses. The optimized structure demonstrates power conversion efficiency (PCE) of 16.39 % for the traditional CIGS based cell whereas the PCE for the CIGS-Si based cell was found to be 23.02 %. The influence of the Si layer thickness on both the low and high-frequency processes was emphasized, highlighting its importance in improving solar cell efficiency.