Highly conductive free-standing reduced graphene oxide thin films for fast photoelectric devices

Abstract

Compared with mechanically exfoliated and chemical vapor deposited graphene, reduced graphene oxide (RGO) possesses unique advantages such as a wet process synthesis, high yield and the ability to assemble large-area thin films on various substrates. However, RGO is normally not recommended for advanced devices owing to its poor electrical conductivity. We report a new method to prepare highly conductive free-standing RGO thin films. The as-prepared RGO thin film possesses the highest conductivity of 87100 S m−1, the second-lowest sheet resistance of 21.2 Ω sq−1 and a medium-level mobility of 16.7 cm2 V−1 s−1 among all of the reported RGO films. To demonstrate the application potential of the free-standing RGO thin films in photoelectric devices, a fully suspended RGO photodetector is constructed using the free-standing RGO thin film, which exhibits the fastest (ca.100 ms) and broadest (from the ultraviolet to terahertz spectral range) photoresponse among all of the RGO film photodetectors that have been reported. The response speed is even comparable with those of CVD-grown graphene photodetectors and mechanically exfoliated graphene photodetectors. These results pave the way towards high-conductivity RGO thin films by a wet process assembly, thus facilitating applications of RGO in advanced electronic, optoelectronic and sensing devices.