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%

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.