Graphene Oxide Thin Films: Synthesis and Optical Characterization

The oxidized derivative of graphene named Graphene oxide (GO) are attractive materials as optoelectronic devices due to their optical response in the mid-infrared wavelength spectral range; however, very large-scaled synthesis methods and optical characterization are required. Here, GO thin films are fabricated on quartz by implementing simple two-step pyrolysis processes by using renewable bamboo as source material. The effect of carbonization temperature (T-CA) on the compositional, vibrational, and optoelectronic properties of the system are investigated. It was found that as T(CA)increases, graphite conversion rises, oxygen coverage reduces from 17 % to 4 %, and the band-gap energy monotonically decreases from 0.30 to 0.11 eV. Theoretical predictions of the energy band-gap variations with the oxide coverage obtained via density functional theory (DFT) computational simulations agree well with the experimental results, providing evidence of oxygen-mediated charge-transport scattering. Interestingly, in the optical response, increased T(CA)results in a blue-shift of the absorption and the absorbance spectrum can be correlated with the large size distribution of the graphitic nano-crystals of the samples. These results suggest that graphene oxide-bamboo pyroligneous acid (GO) thin films exhibit optoelectronic response useful in developing photodetectors and emitter devices in the mid-infrared (MIR) spectral range.