Substitution of Alkali Metal Atoms: An Efficient Approach to Enhance Electronic and Nonlinear Optical Properties of Diamantane

Abstract

Applications of nonlinear (NLO) materials in the fields like electronics, optics, optoelectronics, and optical computing, etc. drive the interest of many scientists to design high-performance NLO materials. Electronic properties, absorption spectra and nonlinear optical properties of alkali metal substituted diamantanes are presented. A significant reduction in HOMO-LUMO gap has been observed by alkali metal substitution. K@CHa has the lowest H-L gap of 1.64 eV as compared to 8.88 eV for pristine diamantane. A remarkable increase in the first hyperpolarizability (βₒ) has been observed due to the substitution of alkali metals. Among these structures, K substituted complexes show the largest first hyperpolarizability (25526-36328 a.u). This significant increase in the first hyperpolarizability (βₒ) is attributed to low crucial transition energies ΔE. K@CHa has the lowest ΔE value (2.0650 eV) which results in the highest βₒ value (36328 a.u.) for K@CHa. Furthermore, frequency-dependent hyperpolarizabilities calculations are carried out using 1906 nm, 1340 nm, and 1064 nm frequencies for commonly used lasers. This study provides an efficient approach to design high-performance NLO materials having extensive applications in the field of electronics and optoelectronics. The results reveal that substitution of alkali metals leads to the shift in absorption from ultraviolet to the visible x region. Bathochromic shifts in the absorption spectra are observed with an increase in the size of alkali metal atom. K@CHa has a maximum absorption wavelength (λmax= 600 nm).