Influence of bi-Alkali Metals Doping over Al12N12 Nanocage on Stability and Optoelectronic Properties: A DFT Investigation

Abstract Bi-alkali metal atoms (Li2, Na2, K2) doped Al12N12 nanocages with remarkable stability are achieved for the first-time using density functional theory. Bi-alkali doping is a highly efficient technique to bring high stability as compared to single alkali metal atom doping. It is revealed that bi-alkali metal atoms doping significantly reduces the wide HOMO-LUMO energy gap (3.93 eV) of pure Al12N12 nanocage to 0.74 eV ∼ 1.67 eV. The reduction in HOMO-LUMO energy gap is due to the formation of new HOMO energy levels having diffused excess electrons which is further confirmed by the PDOS and TDOS plots. The bi-alkali metal atoms doped Al12N12 nanocages exhibit remarkable nonlinear optical response. The highest first hyperpolarizability of 1.2 × 105 au is observed for K2@Ntop. Clearly, the doping of high atomic number atoms brings larger hyperpolarizabilities, while the non-monotonic trend is observed for M2@b66 series where Na2@b66 has a large hyperpolarizability value. These fascinating results will be helpful for achieving the potential applications of inorganic Al12N12 nanocages in the optoelectronic devices and high performance nonlinear optical materials.