Optimization of indium concentration and compositional grading in InGaN heterojunction solar cells by SCAPS-1D simulation

Indium gallium nitride (InGaN) thin-film solar cells exhibit exceptional potential for photovoltaic (PV) applications due to their tunable bandgap (0.7-3.4 eV) and high absorption coefficient (>10(5) cm(-1)). Using SCAPS-1D simulation, this study demonstrates that incorporating compositional grading in the InGaN absorber layer significantly enhances the solar cells performance. Graded InGaN solar cells with optimized Indium (In) concentration achieve superior power conversion efficiency (PCE) compared to ungraded cells. The optimal graded structure, with an In concentration of 0.7, achieves PCE of 36.08%, current density (J(sc)) of 23.52 mA cm(-2), open-circuit voltage (V-oc) of 1.66 V, and fill factor (FF) of 92.1%. In contrast, the ungraded cell exhibits PCE of 34.83%, J(sc) of 22.8 mA cm(-2), V-oc of 1.66 V, and FF of 91.87%. These findings underscore the efficacy of compositional grading in advancing high-efficiency InGaN solar cells.