▎ 摘　　要

NOVELTY - Ultra-large graphene oxide (UL-GO) thin films are formed which involves pre-intercalating sulfuric acid and nitric acid (HNO3) to interlayers of natural graphite flake to form graphite intercalation compound (GIC) powders; expanding of GIC powders at a high temperature; further oxidizing using intercalating agents to exfoliate EG into monolayer graphene oxide (GO) sheets; sequential centrifuging of GO and collecting of UL-GO sheets; preparing of Langmuir-Blodgett (LB) thin films comprised of monolayer UL-GO sheets; and reducing and chemical doping of the UL-GO thin films. USE - The method is useful for forming UL-GO thin films, e.g. optoelectronic UL-GO thin film (all claimed). ADVANTAGE - The method uses an energy-efficient and highly reproducible chemical exfoliation approach to produce gram quantities of UL-GO sheets and develops an inexpensive and high-quality method to deposit them onto a substrate uniformly in an aligned manner. Stable GO colloidal aqueous suspensions are produced by three successive intercalation procedures, namely pre-intercalation of mixed acids, expansion under high temperature and oxidation with strong oxidant agents such as potassium permanganate. Ultrasonication is completely eliminated during the whole process to prevent the breakage of monolayer GO sheets. The resulting films comprising UL-GO sheets with a close-packed flat structure exhibit exceptionally high electrical conductivity and optical transmittance after reduction and chemical doping treatments. Optoelectronic thin films made of the as-prepared UL-GO monolayers by the LB assembly technique are of high electrical conductivity and light transmittance, which have prospect for application in the field of transparent conducting thin films. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for an optoelectronic UL-GO thin film, comprising: layers of UL-GO film having a transmittance of at least 82%, and formed by the method; or an optoelectronic UL-GO thin film, comprising: layers of UL-GO film having a transmittance of at least 82%, and formed by reducing and chemical doping of LB thin films formed by: pre-intercalation of sulfuric acid and nitric acid to interlayers of natural graphite flake to form GIC powders; expansion of GIC powders at a high temperature; further oxidation using intercalating agents to exfoliate EG into monolayer GO sheets; sequential centrifugation of GO and collection of UL-GO sheets; preparation of LB thin films comprised of monolayer UL-GO sheets; and reduction and chemical doping of the UL-GO thin films.