Enhanced non-linear optical response of alkali metal-doped nitrogenated holey graphene (C2N)

•Lowering of HOMO-LUMO energy barrier suggests the possibility of charge mobility in the molecules.•Interaction energies reveals thermodynamic stability of the optimized structures.•Broadened optical absorption was observed in all the doped complexes.•Calculated first order hyperpolarizability indicates that C2N doped complexes are potential candidates for NLO applications. In the quest of better non-linear optical (NLO) materials, a DFT method is employed on alkali metals doped C2N to investigate the optoelectronic characteristics. To understand the optoelectronic properties the charge distribution is a key factor for which frontier molecular orbitals (FMOs), transition density matrix (TDM), density of states (DOS), electron density difference map (EDDM) and molecular electrostatic potential(MEP) analyses were carried out. Interaction energy (Eint) is computed to delve into thermodynamic stability. The projected results of all the complexes is lying in domain of effective NLO materials, like constricted EH-L, reduced Eopt, bathochromic shift in ʎmax and above all upgraded α0 and β0. When compared to C2N, doped complexes display extraordinary NLO response with 1st hyperpolarizability ranging from 2.4 × 104 (K@C2N) to 8.02 × 104 a.u. (Li@C2N). Furthermore, alkali metal doping also lessens the energy gap (EH-L)from 2.3 eV to 2.06 eV in Li@C2N. The nature of vibrations and interactions are probed via IR and NCI analysis. Doped molecules (Li@C2N-K@C2N) do possess greater dipole moment (2.48 D to 5.56 D) than C2N (2.04 D). All characteristics support the use of all doped complexes in integrated NLO devices, paving the way for new approach to computational designing of super-efficient NLO materials. [Display omitted]