Optimization of lead-free BiFeO3 perovskite solar cells for efficient solar-energy conversion in futuristic green technologies

Abstract

The adverse effects of global warming and our dependence on hazardous energy sources, like coal and petroleum, have shifted focus toward solar energy, a sustainable and clean solution. Perovskite materials, particularly BiFeO₃, are attracting attention as absorber layers due to their multifunctional properties. This study employs COMSOL to simulate 1D TiO₂/BiFeO₃/Spiro-OMeTAD solar cells with ideal ohmic contacts at different operating temperatures. Results demonstrate that the short-circuit current density increases with the BiFeO₃ thickness, and efficiency peaks at an optimal thickness. However, the maximum efficiency of 10.88% is achieved (in TiO₂/BiFeO₃/Spiro-OMeTAD) when the electron-transport layer's density of states in the valence and conduction bands (N_CN_V) is ∼2 × 10¹⁶ cm⁻³, while TiO₂/SnS/BiFeO₃/Spiro-OMeTAD shows the maximum efficiency of 20.99% at the SnS layer thickness of 700 nm. Moreover, an increase in BiFeO₃'s bandgap enhances the open-circuit voltage (V_oc) but reduces the fill factor. On the other hand, BiFeO₃'s N_CN_V has no significant impact on efficiency but shows inverse coupling with V_oc. Additionally, increasing BiFeO₃'s electron affinity improves the fill factor, while increasing TiO₂'s and Spiro's electron affinities enhances the V_oc and power output, respectively. This work provides insights for optimizing material properties and device parameters in experimental applications and highlights the potential of BiFeO₃-based perovskites for next-generation photovoltaics.