Alkali metal (Na and Li) doped C18 nanocluster with boosted electronic and nonlinear optical properties

Abstract

To expand the uses of material in nonlinear optics, strategies for producing extraordinary nonlinear optical materials with excess electron compounds are widely known in the literature. In this study, cyclo18 (C18) nanocluster was doped with alkali metals (Na and Li) in such a way that the metal atom was placed inside the C18 surface to explore their nonlinear optical (NLO) properties by density functional theory (DFT) calculations. Alkali metals doping has lowered the band gap energy (4.64–4.55) when compared to the pure surface (6.76 eV). The alkali metals possess loosely bound excess electrons which can be easily excited, hence lowering the doped systems excitation energies, resulting a remarkable increase in the hyperpolarizabilities. The highest value of hyperpolarizability (17,975.051 C3 m3 J-2) has been explored by C18-Na. Moreover, isotropic and anisotropic polarizabilities (αiso and αaniso) were also computed for the alkali doped systems and outstanding outcomes were observed (αiso ranges from 45.69 to 53.07 C3 m3 J-2) and (αaniso ranges 49.91–61.07 C3 m3 J-2), when comparison was made between the doped and undoped surfaces. NCI analysis show that there exist van der Waals interactions among surface and the dopant. Absorption analyses were performed, and the results showed that these doped complexes having excess electrons absorbs at higher wavelength ranging from 675 to 683 nm. Furthermore, FMOs, TDM and NBO analysis revealed the outstanding electronic and charge transfer properties of these doped systems. As a result of our findings, alkali metal doped C18 may be a contender for efficient nonlinear optical characteristics