Graphene Oxide Based Photoelectrical Functional Materials: Designed Preparation And Properties Study

Being a single-layer carbon sheet bearing oxygen-containing functional groups, Graphene oxide （GO） has attracted tremendous attentions in recent years due to its superiority in fabricating graphene and graphene-based composite. Because of the inhomogenous structure with conjugated sp2 clusters embedded within an oxygenated sp3 carbon matrix, GO exhibited peculiar electrical and optical properties. Thus GO was defined as the functionalized graphene, poscess unique basic research and applied values. In this thesis, based on the GO, we have studied its optical properties, and constructed the model of its band structure- multi-quantum well; we have also studied its photochemical properties, and proposed the concept of controlling micro-structure and electrical,optical properties via selecting the waveband of irradiation; finally we have designed and fabricated the GO-TiO₂ and GO-nobel metal functional composites, analyzed the effect of UV-irradiation on the electrical property of GO-TiO₂ composite film, and realized the Photo-assisted preparation and patterning of reduced GO-TiO₂ conductive thin film.The optical property of GO was studied in term of the absorption and photoluminescence （PL） spectra. Results indicated that there is a wide distribution of the localized states within GO, and its band structure can be well described by the model of multi-quantum well. This model can give the reasonable explanation of its absorption and PL properties. The PL behaviors of the sp2C clusters with different sizes have been studied through temperature dependent PL excited by different wavelength. The results indicated that the smaller clusters have the more stable PL. In addition, we build up a simple method to judge the effect of the reduced GO （RGO） with different reduction methods, which is very important for designing and exploring effective reduction methods.The photochemistry of GO was studied, and also the influence of its special band structure on the photochemical property. Results indicated that under the irradiation whose wavelength is shorter than 520 nm, photoreduction of GO itself in air was observed, and behaved obviously dependent on the phonon energy, which was closely associated with the special band structure of GO. This suggested the possibility to tuning the micro-structure of GO by selecting the waveband of irradiation, which correspondingly influenced the micro-structure, the electrical and optical properties of GO films. Moreover, the photochemical activity of GO can be used to prepare GO-nobel metal nanoparticle composites, which provided a new route to fabricate GO-nobel metal nanoparticles compostes. Finally, these studies provided a value reference for stability of GO.The fabrication of large-area reduced GO-TiO₂ conductive thin film and micropatterns via a UV-assisted approach were firstly investigated. The result indicated that the PH values of the GO-TiO₂ colloidal suspension and the molar ratio of GO and TiO₂ was the key factor to control the quality of the film and the reduction of GO. Under UV irradiation, the photogenerated electrons could be efficiently captured by the sp2 regions to reduce GO film. The resistance of photo reduced GO-TiO₂ film can reach 2 S/cm,a level similar to chemically reduced GO films. Patterned PRGO-TiO₂ films can be conveniently fabricated by UV irradiation through photomasks with a line width as thin as Micrometer. And because of the weak heat effect of UV light, the photo-assisted reduction method is particularly suitable for the fabrication of reduced GO patterns on flexibleplastic substrates. Thus, this method may have potential applications in future flexible electronic device and integrated electronic devices.