Optical properties of armchair graphene nanoribbons with Stone-Wales defects and hydrogenation on the defects

Armchair graphene nanoribbon (AGNR) is one of the most investigated semiconducting graphene materials. The controllable approach on AGNR is quite useful for future optical applications. To realize the aim, optical properties of three AGNRs with Stone-Wales (SW) defects and hydrogenation on the SW defects (SW-H) are theoretically investigated. W8, W9 and W10 AGNRs are chosen based on the width (W) index of n. SW defects enlarge the band gap of W8, and reduce the band gap of W9 and W10. The hydrogenations increase the band gaps of W8- and W9-SW, and decrease the one of W10-SW. The distributions of exciton wavefunctions located near one edge of W10-SW-H, revealed an obvious quantum confinement effect. In W10 serials, the exciton binding energy difference between SW and SW-H structures is only 0.08 eV, indicating tuneable optical applications with this small exciton binding energy switch. Due to the strong optical absorption and small exciton binding energy of W9-SW, it also possesses potential applications for luminescence and photovoltaic devices.