Synthesis and Superior Optical-Limiting Properties of Fluorene-Thiophene-Benzothiadazole Polymer-Functionalized Graphene Sheets

A polymer based on fluorene, thiophene, and benzothiadazole as the donor-spacer-acceptor triad is covalently coupled to reduced graphene oxide (rGO) sheets via diazonium coupling with phenyl bromide, followed by Suzuki coupling. These polymer-graphene hybrids show good solubility in organic solvents, such as chloroform, tetrahydrofuran (THF), toluene, dichlorobenzene, and N,N-dimethylformamide (DMF), and exhibit an excellent optical-limiting effect with a 532-nm laser beam. The optical-limiting threshold energy values (0.93 J cm(-2) for G-polymer 1 and 1.12 J cm(-2) for G-polymer 2) of these G-polymer hybrids are better than that of carbon nanotubes (3.6 J cm(-2)).