Remarkable nonlinear optical response of alkali metal doped aluminum phosphide and boron phosphide nanoclusters

Continuous strides are made to realize molecular systems with exceptionally high nonlinear optical response. Here, we report alkali metal exohedrally doped phosphide nanocages as the excellent materials with remarkable nonlinear optical response. Density functional theory calculations have been performed for geometric, diffusion kinetics, electronic, linear and nonlinear optical properties of exohedral alkali metal doped aluminum phosphide and boron phosphide (M@Al12P12 and M@B12P12) nanocages. All possible doping sites are evaluated for geometric, electronic and nonlinear optical properties. The kinetic stabilities of the doped structures are evaluated through diffusion barriers. Adsorption energies reveal that all structures are thermodynamically very stable. Doping of alkali metal significantly influences the properties of nanocages. HOMO-LUMO (H-L) gap is reduced significantly whereas hyperpolarizability is increased several orders of magnitude. The dramatic change in HL gap is observed for Na@P-tcp-Al12P12 whereas maximum hyperpolarizability is calculated for K@P-tcp-B12P12. The H-L gap of Na@P-tcp-Al12P12 is about 0.94 eV compared to 3.36 eV of pure AIP nanocage. Remarkably high hyperpolarizability of 7.9 x 105 au for K@P-tcp-B12P12 is comparable to the highest reported hyperpolarizabilities in the literature. Furthermore, Al/Btop and Ptop doped nanocages show relatively higher hyperpolarizability values compared to other doped structures. (C) 2018 Elsevier B.V. All rights reserved.