Preparation And Properties Of Copper Nanowires Based Transparent Conductive Films

Tin-doped indium oxide(ITO)based transparent conductive films have been widely used in various optoelectronic devices owning to their excellent optical and electrical properties.However,researchers have devoted to find the substitute of ITO because of its weakness in high cost,rare resource,poor in flexibility.Fortunately,one dimensional copper nanowires(Cu NWs)have attracted ever-growing attention as a low-cost candidate for indium tin oxide for use as a transparent electrode due to its good combination of high electrical conductivity,mechanical property and optical property.Accordingly,the dissertation concentrates on the synthesis of Cu NWs,the fabricating of nano-network based transparent conductive films(TCFs)as well as the anti-oxidation performance study.The main details and conclusions are as follows:1.Hydrothermal method was used to synthesize Cu NWs at a moderate temperature,in which CuCl2·2H2O,glucose,oleylamine and oleic acid,polyvinylpyrrolidone(PVP)were acted as copper precursor,reducing agent,capping agent,dispersing agent respectively.The mount of reducing agent,capping agent,dispersing agent as well as the reaction time were all-aroundly studied in controlling the morphology of the final products.The crystal structure,morphology,element of the prepared products were investigated by X-ray diffraction(XRD),scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray photoelectric spectroscopy(XPS)respectively.In a standard experiment,face-centered cube structured Cu NWs with length of 70μm and diameter of 65 nm were obtained,and the results showed that the Cu NWs grown from poly-crystalline particle and grown along [110] direction.2.Cu NWs based transparent conductive films were fabricated by filtration method.Firstly,Cu NWs dispersed in isopropyl alcohol were filtrated onto a filter membrane.Immediately,the filter membrane with Cu NWs was attached to polyethylene terephthalate(PET)substrate or glass substrate with mechanical press(by 2 kg weight)for few seconds to make the Cu NWs transferred to target substrate.By changing the volume the diluted Cu NWs,films with varied density were achieved.The as-prepared films were not conductive until post treatment conducted.The results showed that,a simple chemical dipping treatment in glacial acetic acid for 30 s contributes to enhanced optical and electrical properties(Cu NWs/PET,T=90%,60Ω/sq),which achieved comparable performance(Cu NWs/glass,T=90%,55Ω/sq)to that of high temperature annealed in inert gas.Importantly,Cu NWs/PET films exhibit outstanding flexibility,no obvious improvement in sheet resistance happen after 1000 times bengdig test.3.A top AZO layer was deposited on Cu NWs/PET films by radio frequency magnetron sputtering to improve anti-oxidation properties.The thickness of AZO layer was controlled to obtained supreme optical and electrical performance with enhanced antioxidation properties.As a result,the transmittance decreased and sheet resistance increased as the AZO layer began to thicken.When the sputtering time was kept at 30 min,AZO/Cu NWs/PET(transmittance 85% and sheet resistance 62Ω/sq)sheet resistance increased by 2.4% after stored for 50 days(relative humidity 80%,temperature 30℃),which demonstrated the good anti-oxidation properties of AZO/Cu NWs/PET films.However,as a comparision,the sheet resistance of Cu NWs/PET films without a AZO coating layer increased sharply after stored for a few days at the same condition.