Functionalized reduced graphene oxide with tunable band gap and good solubility in organic solvents

The materials intended for organic photovoltaics and organic electronics require specific properties, such as conjugation along backbones, good solubility in organic solvents and a suitable band gap. Graphene oxide holds a high indirect optical band gap of 3 eV and a hydrophilic behavior. However, based on the fact that the graphene oxide band gap is related to the C/O ratio, chemical reduction and functionalization must be performed to obtain the proper characteristics that are required for organic applications. Here an efficient approach for chemically modified graphene oxide as a low-cost alternative for organic semiconductor materials was developed. The two synthesized materials (functionalized reduced graphene oxide and functionalized reduced graphene oxide decorated with silver nanoparticles) exhibited a 65% and 52% band gap decrease respectively, compared to graphene oxide. Moreover, both materials were soluble in organic solvents at high concentrations [10 mg mL−1], turning them suitable for many applications, including organic electronics, with the additional advantage of being a solution process avoiding restacking of layers.