Numerical Investigation and Optimization of a GeSe/Sb2Se3 Double Absorber Layer Thin-Film Solar Cell Using SCAPS-1D

Abstract

In this study, a novel FTO/SnS2/GeSe/Sb2Se3/NiOx/Au double absorber layer thin-film solar cell is designed and numerically optimized using the SCAPS-1D simulator. The device employs earth-abundant, non-toxic absorber materials (GeSe and Sb2Se3) with favorable optoelectronic properties, SnS2 as the electron transport layer, and NiOx as the hole transport layer. A systematic parametric study is performed on the thickness, defect density, and doping concentration of each functional layer to identify the dominant performance-limiting factors. The non-optimized baseline device yields a power conversion efficiency (PCE) of 20.70%, with an open-circuit voltage (Voc) of 0.82 V, a short-circuit current density (Jsc) of 40.64 mA/cm2, and a fill factor (FF) of 62.12%. The analysis reveals that the GeSe/Sb2Se3 interface defect density is the primary factor governing device performance; reducing it from 1012 to 1010 cm-2 significantly enhances Voc from 0.82 V to 1.05 V. The fully optimized device achieves a theoretical PCE of 29.69% (Voc = 1.05 V, Jsc = 41.57 mA/cm2, FF = 67.96%) under standard AM 1.5G illumination at 300 K, while incorporating series (3 Ω·cm2) and shunt (1000 Ω·cm2) resistances yields a more realistic PCE of 24.84%. These results demonstrate that the proposed heterostructure is a promising candidate for next-generation lead-free thin-film photovoltaics.