Predicting efficiencies >25% A3MX3 photovoltaic materials and Cu ion implantation modification

Halide perovskite exhibits remarkable photovoltaic (PV) performance so far, however, its toxicity and instability hinder the commercialization. Researchers are devoted to explore nontoxic and stable solar cell alternatives with high efficiency. Considering the octahedra network and the high symmetry crystalline structure of prototype Mg3NF3 (Pm-3m), which is similar to the halide perovskites and tends to create high p-s band edge states transition probability associated closely with the excellent PV performance. We extensively screened the potential PV materials from 64 compounds in A3MX3 (A = Mg, Ca, Sr, Ba; M = N, P, As, Sb; X = F, Cl, Br, I) structure based on the bandgap, theoretical efficiency, band edge states transition, and thermal stability. Three Pb-free compounds, i.e., Ba3PI3, Ba3AsI3, and Ba3SbI3, are found to be ideal stable PV materials with the efficiency (25.9%) comparable to that of halide perovskites. The optical absorption of the best PV candidate, i.e., Ba3SbI3, has been improved further by low energy Cu ion implantation, and the occurrence of the threshold velocity in the electronic stopping power and the derived bandgap confirm again the high accuracy of our density functional theory results.