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 (β0). Especially, three interesting relationships between the defect structure and β0 value are observed. We found that the defects (for example, the Stone–Wales and 585 defects) in graphenes can greatly enhance β0 values up to 1.4 × 105 au (about 1200 × 10−30 esu), which shows that the defect is a new factor for enhancing β0 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.