Optimization of ultrathin Mg-doped ZnO layer for efficient charge carrier extraction in BiFeO3-based solar cells

Abstract

As the world moves towards more sustainable energy, research into multifunctional oxide-based solar cell designs presents exciting substitutes for established technology. In this study, a one-dimensional single-junction device structure Mg-doped ZnO (MZO)/BiFeO3 (BFO)/Cu2FeSnS4 (CFTS) was numerically simulated using COMSOL Multiphysics, aiming to analyze its optoelectronic behavior under varied physical conditions. The core absorber (BFO) was chosen for its unique integration of ferroelectricity, magnetism, and suitable bandgap properties, enhancing charge separation and light absorption. The device achieved a maximum short-circuit current density of 8.96 mA/cm2 at a donor density of 1×1016 cm-3, while the highest open-circuit voltage of 0.93 V was observed at 250 K. Notably, a fill factor of 78.99% was recorded at 390 K, and the optimum efficiency of 5.45% emerged at 285 K under a donor density of 1×1018 cm-3. These results suggest strong potential for oxide-based multiferroic absorbers in future photovoltaic platforms, especially for reliable, temperature-resilient, and environmentally sustainable energy applications.