A New Strategy of bi-Alkali Metal Doping to Design Boron Phosphide Nanocages of High Nonlinear Optical Response with Better Thermodynamic Stability

Abstract

Nonlinear optical materials possess high rank in fields of optics owing to their impacts, utilization and extended applications in industrial sector. Therefore, design of molecular systems with high nonlinear optical response along with high thermodynamic stability is a dire need of this era. Hence, the present study involves investigation of bi-alkali metal doped boron phosphide nanocages M2@B12P12 (M = Li, Na, K) in search of stable nonlinear optical materials. The investigation includes execution of geometrical and opto-electronic properties of complexes by means of density functional theory (DFT) computations. Bi-doped alkali metal atoms introduce excess of electrons in the host B12P12 nanocage. These electrons contribute towards the formation of new HOMO, thus reducing HOMO-LUMO gaps. The reduced HOMO-LUMO gap ranges from 0.63eV to 3.69eV. The diffused excess electrons also come up with increased hyperpolarizability values of complexes i.e. up to 4.0×104au. TD-DFT calculations have been performed to examine crucial transition states and for UV-VIS analysis. IR and DOS spectra have been plotted to support our obtained results. Non covalent interaction (NCI) calculations along with quantum theory of the atoms in molecules (QTAIM) analysis were carried out to understand the bonding interactions between alkali metal atoms and B12P12 nanocage. All obtained results suggest bi-alkali metal doped nanocages as exceptionally stable materials with improved NLO response and superb candidates for their vast applications in optics.