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 C 2 N 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 (Li, Na, K) doped C 2 N to investigate the optoelectronic characteristics. To understand the optoelectronic properties the charge distribution is a key factor for which frontier molecular orbitals (FMOs), density of states (DOS), transition density matrix (TDM), molecular electrostatic potential (MEP) and electron density difference map (EDDM) analyses were carried out. Interaction energy (E int ) is computed to delve into thermodynamic stability. The projected results of all complexes lie in domain of effective NLO materials, such as constricted E H-L , reduced E opt , bathochromic shift in ʎ max and above all upgraded α 0 and β 0 . When compared to C 2 N, doped complexes display extraordinary NLO response with 1 st hyperpolarizability ranging from 2.4×10 4 (K@C 2 N) to 8.02×10 4 a.u. (Li@C 2 N). Furthermore, alkali metal doping also lessens the energy gap from 2.3 eV in C 2 N to 2.06 eV in Li@C 2 N. The nature of vibrations and interactions are probed via IR and NCI analysis. Doped molecules (Li@C 2 N-K@C 2 N) do possess greater dipole moment (2.48 D to 5.56 D ) than C 2 N (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.