Performance Improvement of CIGS Thin-Film Solar Cells by Incorporating an ITO Photoanode and Designing a Structured Back Layer

Document Type : Original Article

Authors
Majid Fouladian
Reza Kiani
Seyed Mahmoud Jalal Rastgar Fatemi
Faculty of Electrical Engineering - Saveh Branch, Islamic Azad University, and Saveh, Iran
10.22034/jcse.2025.537565.1057
Abstract
Copper Indium Gallium Selenide (CIGS) thin-film solar cells are well known for their intrinsic stability and suitable direct bandgap, making them promising candidates for high-efficiency photovoltaic applications. This study aims to improve the performance of CIGS solar cells by incorporating pitch-like gaps in the back contact layer to reduce minority carrier recombination. Using Silvaco TCAD simulations, the effects of various gap widths and material properties on cell efficiency were analyzed. Results indicated that an optimal gap width of 200 nm, combined with increased doping concentration and charge density in the absorber layer above 1 cm⁻³, significantly boosted performance. Additionally, tuning the doping profiles of other layers mitigated the adverse effects of the back layer's high resistivity and low conductivity. Furthermore, integrating a transparent ITO photoanode improved front-side light transmission. Collectively, these design modifications increased the device efficiency from 20.8% to 27.5%, demonstrating a substantial improvement in both optical and electrical characteristics of the CIGS solar cell architecture.
Keywords
CIGS solar cells
minority carrier recombination
back layer engineering
Silvaco simulation
ITO photoanode