Covalent functionalization of graphene oxide with hyperbranched lanthanum phthalocyanines for improving optical limiting

Abstract

Abstract Two graphene oxide (GO)-based nanohybrid materials possessing axially covalent linkages to lanthanum phthalocyanines (LaPc-GO) and hyperbranched lanthanum phthalocyanines (HBLaPc-GO) were prepared. Significant fluorescence quenching demonstrates electron transfer between lanthanum phthalocyanine precursors and GO. At the identical mass concentration of 0.1 mg mL−1, all the hybrids show stronger nonlinear optical (NLO) performance than the individual components, ascribed to a combination of nonlinear scattering and two-photon absorption with reverse saturable absorption and the photoinduced electron or energy transfer from the electron donor phthalocyanine moiety to the acceptor graphene. Due to the better dispersion and the more flexible electron/energy transfer, the HBLaPc-GO exhibits a stronger optical limiting response (the normalized transmittances decrease to 49%) and a larger nonlinear extinction coefficient (1.48 cm GW−1) than that of LaPc-GO hybrid.