A comparative numerical simulation study of CIGS solar cells with distinct back surface field layers for enhanced performance

The objective of this study is to explore the impact of various back surface field (BSF) layers including copper aluminium oxide (CuAlO₂), Copper Antimony Sulphide (CuSbS₂), Formamidinium tin triiodide (FASnI₃), poly (3-hexylthiophene) P3HT to boost the output of conventional baseline CIGS solar cells structured. The device performance increases because of the minimized surface recombination velocity through heavily doped BSF layers, which increases the electric field at the rear contact. Among all proposed BSF layers CuAlO₂ gives the best photoconversion efficiency (η) of 24.61 % followed by fill factor (FF) of 83.11 %, short circuit current density (J_SC) of 35.87 mA/cm², and open circuit voltage (V_OC) of 0.82 V with quantum efficiency (QE) of ∼92 % for the whole visible range with the onset happening at ∼ 560 nm, thanks to the enhancement of carrier collection when BSF layer is incorporated. The novelty in this work is that for the first time with the CuAlO₂ BSF layer, 24.61 % efficiency is reported at 1 μm CIGS layer thickness. We also examined how different BSFs affect the PV performance of the devices. The effect of temperature, the doping concentration of the BSFs, varying gallium proportion, JV & QE analysis, band diagram, and radiative recombination coefficient are varied to observe their impact on the PV parameters. This research introduces novel CIGS/CdS heterojunction configurations using various BSF layers to enhance efficiency, supporting the advancement of ultrathin, flexible, and tandem solar cell applications.