Turning diamondoids into nonlinear optical materials by alkali metal Substitution: A DFT investigation

• DOI: 10.1016/j.optlastec.2021.107231
• Publication Date: 2021-05-25T09:59:12Z
• Authors: Palwasha Khan; Tariq Mahmood; Khurshid Ayub; Sobia Tabassum; Mazhar Amjad Gilani
• Keywords: Diamondoid; Substitution (logic)

Abstract 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 energy (ΔE). K@CHa has the lowest ΔE value (2.06 eV) which results in the highest βo value (36328 a.u.) for K@CHa. Furthermore, frequency-dependent hyperpolarizability calculations have been carried out using 1906 nm and 1340 nm frequencies for commonly used lasers. The values of dynamic hyperpolarizabilities are greater than those of static ones for the majority of the substituted systems. This suggests the application of the proposed complexes under different frequencies of incident radiations. The substitution of alkali metals leads to the shift in absorption from ultraviolet to the visible region. Bathochromic shifts in the absorption spectra are observed with an increase in the size of alkali metal atom (λmax = 600 nm for K@CHa). This study provides an efficient approach to design high-performance NLO materials having extensive applications in the field of electronics and optoelectronics.