Design of a novel eco-friendly bismuth-based solar cell by first-principles calculation and device simulation

Abstract

The development of high-efficiency and environmentally light-absorbing materials is a big challenge in the field of photovoltaics. Post-transition-metal-based materials exhibit excellent optoelectronic properties. Motivated by this, we investigated the optoelectronic properties of a series of bismuth-based materials Na₃BiX₄ (X = O, S and Se) based on the density functional theory and employed the SCAPS-1D to assess their potential in the application of photovoltaic devices. The electronic structures are calculated by the hybrid functional method, and the sulfide Na₃BiS₄ is predicted to possess an optimal direct bandgap of 1.699 eV. The effective masses are estimated to be 0.671 m₀ for electrons and 0.697 m₀ for holes, respectively. The exciton binding energy further confirms the exceptional carrier mobility of the sulfide Na₃BiS₄. The absorption coefficients reveal the desired light-harvesting capabilities within the visible range, which can result in a power conversion efficiency of over 24 % for the Na₃BiS₄ thin film with a typical thickness of 0.5 μm. We further analyzed the influence of various charge transport materials on the photovoltaic performance of Na₃BiS₄-based solar cells. Given the large electron affinity, optimizing the interface characteristics and the open-circuit voltage is predicted to be a feasible approach to improve the photovoltaic performance.