In Silico Modelling: Electronic Properties of Phosphorene Monoflakes and Biflakes Substituted With Al, Si, and S Heteroatoms

Abstract

This contribution explores the systematic substitution of monoflakes (Mfs) and biflakes (Bfs) phosphorene with aluminum, silicon, and sulfur. All this was investigated using functional TPSS and CASSCF calculations. Al and Si substitution produces significant structural changes in both Mfs and Bfs compared to S-substituted and pristine systems. However, in Mfs, all heteroatoms generate a decrease in band gap and the ionization potentials (IP), and an increase in electron affinity (EA) in comparison with pristine phosphorene. Al doping improves the hole mobility in the phosphorene monoflake, while Si and S substitutions exhibit a similar behavior on EAs and reorganization energies. For Bfs, the interlaminar interactions Si-Si and Al-P cause structural changes and higher binding energies for Si-Bfs and Al-Bfs. Regarding the electronic properties of Bfs, substitution with Si does not produce significant variations in the band gap. However, it conduces to the formation of hole transport materials concerning its monolayer counterpart. It also is observed in Al-systems, whereas for S-complexes, no correlation was identified between the doping level and reorganization energies. Also, the substitution with Al and S leads to an opposite behavior of the band gap and IP values, while the variation in EA is similar. In summary, the nature of heteroatom and the doping degree can modify the semiconductor character and electronic properties of phosphorene mono- and the biflakes, whose trends are closely related to the atomic properties of heteroatoms considered. Overall, these computational calculations provide significant insights into the study of doped phosphorene materials.