The Dion–Jacobson perovskite CsSbCl4: a promising Pb-free solar-cell absorber with optimal bandgap ∼1.4 eV, strong optical absorption ∼105 cm−1, and large power-conversion efficiency above 20%

Abstract

Organic–inorganic hybrid Pb-based halide perovskites, especially the well-known MAPbI₃, have shown great promise for photovoltaic applications due to their fast-growing power-conversion efficiency (PCE) and low manufacturing cost. However, their poor ambient stability and Pb-toxicity are still challenging issues for future commercialization. Here, by combining first-principles calculations with large-scale screening, we propose a Pb-free all-inorganic Dion–Jacobson perovskite CsSbCl₄, which has an optimal bandgap (∼1.4 eV) in the first place. Our calculations also show that CsSbCl₄ possesses high carrier mobility (∼10²–10⁴ cm² V⁻¹ s⁻¹) and strong interband optical absorption (∼10⁵ cm⁻¹). Consequently, its spectroscopic limited maximum efficiency can reach up to ∼27%, similar to MAPbI₃. Moreover, the TiO₂/CsSbCl₄/spiro-OMeTAD junction has a PCE of 20.07%, which can be further enhanced by optimizing parameters, such as absorber defect density. These favourable characteristics of CsSbCl₄ make it a potential alternative to Pb-based halide perovskites in photovoltaic devices.