Substituted graphene nano-flakes: Defective structure and large nonlinear optical property

Substituted graphenes without centrosymmetry can be considered as a new acceptor-graphene model for NLO materials and exhibit large static first hyperpolarizabilities ( β 0 ). Especially, three interesting relationships between the defect structure and β 0 value are observed. We found that the defects (for example, the Stone–Wales and 585 defects) in graphenes can greatly enhance β 0 values up to 1.4 × 10 5 au (about 1200 × 10 −30 esu), which shows that the defect is a new factor for enhancing β 0 value. Meanwhile, large HOMO–LUMO gaps (4.595–5.982 eV) and vertical ionization potential values (8.059–13.572 eV) indicate that those substituted graphenes molecules have chemical stabilities.