Enhanced electronic and non-linear optical properties of alkali metal (Li, Na, K) doped boron nitride nano-cages

Abstract

Geometrical, electronic and nonlinear optical (NLO) properties of several alkali metal doped boron nitride nanocages (MB12N11 and MB11N12) are explored theoretically. NLO (Non Linear Optical) properties are obtained through first hyperpolarizability, and rationalized on the basis of dipole moment change during excitation to crucial transition state, and band gap. It is revealed that first hyperpolarizability (β0) is increased to a larger extent (1.3 × 104 au for KB12N11) in doped boron nitride nanocages as compared to pure B12N12 (0 au). MB12N11 nanocages show an increasing trend of β0 and βvec with increase in atomic number of alkali metal, in contrast, MB11N12 nanocages show unmonotonic dependency. Further, HOMO-LUMO gap is lowered significantly since a new level is introduced near Fermi level in all doped structures. All the doped structures show n-type semiconductor properties due to diffuse excess electrons in the system which give rise to new HOMO. The present idea offers potential application of these nanocages in new kind of electronic devices and is helpful in designing novel high-performance NLO materials.