Structure and optical property of functionalized reduced graphene oxides as electron acceptors in polymer solar cells

Graphene oxide (GO) prepared by the Hummers method was hydrothermally reduced for 5 and 10 h to obtain 5-RGO and 10-RGO, respectively. The GO and RGOs reacted with phenyl isocyanate to obtain three solution-processable functionalized graphenes (SPFGO, 5-SPFRGO and 10-SPFRGO), which were used as electron acceptors to prepare composite films with poly 3-hexylthiophene (P3HT) as an electron donor in polymer solar cells. Results indicate that GO consists of about 3-5 layers, and the RGOs still have some oxygen-containing functional groups such as —COOH and CO after the reduction. Functionalized GOs have good dispersibility in dichlorobenzene and exhibit energy levels matching P3HT, indicating that they can be used as the electron acceptor materials of polymer solar cells. A5-SPFRGO/P3HT composite film exhibits good compatibility, strong light absorption and obvious fluorescence quenching, suggesting that 5-SPFRGO is an excellent electron acceptor material.