A DFT study on M3O (M = Li & Na) doped triphenylene and its amino-, hydroxy- and thiol-functionalized quantum dots for triggering remarkable nonlinear optical properties and ultra-deep transparency in ultraviolet region

Abstract

Motivated by the excellent geometric and electronic properties of recently reported triphenylene (TP), for the first time, we studied the nonlinear optical responses of superalkalis (Li3O and Na3O) doped triphenylene and amino (HATP), hydroxy (HHTP) and thiol (HTTP) functionalized quantum dots by using density functional theory. The geometric stabilities of eight reported complexes are measured through the interaction energies at ωB97XD/6-31+G(d,p) level of theory. Our results reveal that Li3[email protected] and Na3[email protected] complexes are highly stable with the interaction energies of −60.36 and −57.26 kcal/mol, respectively. The HOMO-LUMO energy gaps of TP, HATP, HHTP and HTTP are significantly varied upon complexation with M3O which is evident by the strong charge transfer from excess electron donor superalkalis (M3O) to the surfaces. However, the π back donation is more pronounced in M3[email protected] complexes, revealed by the negative value of CHELPG charge transfer on M3O. Due to the donation and back donation of charges between M3O and HATP, the significantly high first static hyperpolarizability (βo) and its projection to dipole moment (βvec) are computed for M3[email protected] complexes. The βo of Li3[email protected] and Na3[email protected] complexes are 3 × 104 au. The βo of Na3[email protected] complex is surprisingly high (1 × 105 au) which is justified by the two-level model. Moreover, the NLO responses of co-doped Li3O/Na3O and mixed functional groups TP-quantum dots are also computed. Among them, the maximum βo (5 × 104) is observed for the Na3[email protected] complex. Finally, the TD-DFT calculations reveal that the reported complexes show excellent transparency in the ultraviolet region especially M3[email protected] and Na3[email protected] complexes.