Numerical optimization of cesium bismuth iodide-based CIGS/Perovskite tandem solar cells for enhanced photovoltaic performance

Perovskite solar cells have gained significant attention due to their high efficiency. This study presents a comprehensive numerical modeling of CIGS/Perovskite bilayer solar cells aimed at enhancing their performance. Utilizing advanced device simulation software, we investigate the impact of integrating cesium bismuth iodide-based perovskite with a second-generation CIGS absorber layer. The model evaluates critical parameters including layer thickness, defect density, doping concentration, band gap, and temperature to optimize device architecture. Initial simulations of the baseline structure, featuring SnO2 as the electron transport layer (ETL) and CuSCN as the hole transport layer (HTL), reveal a power conversion efficiency (PCE) of 5.75 %, a fill factor (FF) of 42.9 %, a short-circuit current density (Jsc) of 11.26 mA/cm², and an open-circuit voltage (Voc) of 1.19 V. Through targeted optimization, we achieve significant performance enhancements, increasing the PCE to 15.69 %, the FF to 89.34 %, the Jsc to 12.43 mA/cm², and the Voc to 1.41 V. The optimized device structure FTO/SnO2/Cs3Bi2I9/CIGS/CuSCN/Pt demonstrates a promising pathway for developing efficient and environmentally friendly perovskite solar cells. This study underscores the potential of tandem cell configurations in achieving stable, high-efficiency, lead-free photovoltaic solutions.