Lead-free perovskites using divalent superatom ions with tunable electronic structures and high efficiency

Abstract

Lead halide perovskites with the ABX3 formula are limited by their small B-site ions, which hinder the incorporation of large ions into their three-dimensional BX3 frame. Through high-throughput computational screening based on first-principle calculations and stringent structural constraints, we identified two promising candidates from 81 initial perovskites. These optimized materials feature a quasi-cubic, lead-free structure with a direct band gap suitable for solar cell applications, and minimal deformation of ions. The quasi-cubic (SCs3)(CLi6)F3 superatom perovskite exhibit the direct band gap, s−p and p−p electron transitions, small carrier effective masses, and high efficiency. Additionally, (SCs3)(CLi6)F3 superatom perovskite demonstrate N-type and P-type characteristics through occupying sulfur vacancies with Cl and P atoms, respectively, indicating that they may be used as electron and hole transport layers. This work implies the potential of superatom perovskites to overcome limitations of traditional perovskites.