Effect of Gold Nanoparticles on Optoelectronic Properties of Thermally Reduced Graphene Oxide
Abstract
Gold nanoparticles (AuNPs)-decorated reduced graphene oxide (rGO) is a compelling material from both aspects of processing and functionality. This paper presents an alternative method to prepare and alter the optoelectronic properties of the AuNPs-rGO hybrid film. Au was sputtered for a duration of 0–60 s on graphene oxide (GO) film before subjected to thermal reduction at 700∘C. The surface of rGO was decorated by spherical AuNPs with a mean particle size of around 10nm due to the solid-state dewetting process. The surface plasmon resonance (SPR) of AuNPs around 550nm was intense when the Au sputter duration exceeded 20s. Remarkably, the AuNPs layer retarded the de-oxygenation of GO during thermal annealing. The AuNPs-rGO hybrid film with long-duration Au sputtering exhibited low optical constants and thicker rGO film. The AuNPs also played the role in lowering the bandgap, increasing the lattice disorder and assisting the high-energy photon absorption in the thermally reduced rGO film. The sample of 30s and 40s Au sputtering was optimum to obtain the lowest sheet resistance of 59kΩ/sq and 56kΩ/sq, respectively. The sheet resistance was bargained between de-oxygenation retardation and doping by the AuNPs. Both samples of 30 s and 40 s Au sputtering were having a unique and satisfyingly strong absorption band around 260nm, 350nm and 555nm corresponding to n−π* transition, π−π* transition and SPR of AuNPs, respectively. Such properties are desirable in several applications such as a transparent electrode and optoelectronic sensor.
