Investigating the Electronic Properties of Graphene Quantum Dot Substituted with Group III and Group V Elements

Graphene quantum dot (GQD) was substitutionally doped with group III (Al, Ga, In) and group V (P, As, Sb) elements to tailor their electronic and stability properties. Density Functional Theory (DFT) at the B3LYP/LANL2DZ level was used to evaluate total dipole moment (TDM), energy gap (ΔE), molecular electrostatic potential (MESP), HOMO-LUMO frontier orbitals, density of states and its projection (DOS/PDOS). Doping reduced the bandgap, with group III dopants yielding moderate gaps (~2.4-2.6 eV) and p-type behavior, whereas group V dopants produced lower gaps (~0.85-0.90 eV) for P and Sb, except As at (2.87 eV) and n-type conductivity. DOS analysis revealed new electronic states that may enhance charge carrier separation and transport and PDOS exhibited the significant contribution for the dopant atoms. Global reactivity descriptors indicate that doping alters ionization potential, electron affinity, and chemical hardness, further tuning GQD electronic structure. Quantum Theory of Atoms in Molecules (QTAIM) and non-covalent interaction (NCI) analyses indicated that group V dopants form stronger covalent bonds compared to the interactions observed for group III dopants. Complementary IR analysis and frequencies mods comparison validated the structural models and computational mythology. These results highlight the potential of doped GQDs for organic semiconductor applications.