Exploring novel anti-perovskites X4A2O (X = K, Rb, Cs; A = Cl, Br, I) with excellent photoelectric performance towards photovoltaic applications

Abstract

The development of advanced solar cell materials with high light absorption, superior carrier mobility, and significant power conversion efficiency (PCE) still poses significant challenges. Lead-free anti-perovskites, with their flexible structure, non-toxicity, and suitable bandgap width, show great application prospects. Here, we designed a series of anti-perovskite X₄A₂O (X = K, Rb, Cs; A = Cl, Br, I) structures with high exceptional structural stability and excellent optoelectronic properties, and studies these using density functional theory (DFT) calculations. All X₄A₂O compounds possess high electron mobility in the z-direction (1.55 × 10³–53.56 × 10³ cm² V⁻¹ s⁻¹), which is significantly larger than that of MAPbI₃ (∼164 cm² V⁻¹ s⁻¹). The PCEs of five types of X₄A₂O exceed that of MAPbI₃, especially that of Rb₄Br₂O of about 31.04%. Furthermore, the J–V curve indicates that all X₄A₂O have a higher fill factor (FF) than Si and MAPbI₃. These results confirm that X₄A₂O should be a promising candidate for the light-absorbing layer in solar cells, demonstrating its potential applications in the photovoltaic and photoelectric fields.