The Synthesis Of Copper Nanowires And The Application For Transparent Conductive Films

Copper nanowires?CuNWs?have attracted great interest of domestic and foreign researchers due to their high transparency,flex resistance,efficient electrical etc.Besides,copper costs much less than silver or indium,but its electrical conductivity is close to silver.Copper nanowires films have therefore emerged as a perfect alternative to AgNWs or ITO for fabricating low-cost transparent conductive film.In this thesis,we prepared the CuNWs by a wet chemical method.By studying its growth process,a novel growth mechanism was proposed in this work.In addition,we studied the various factors of different reaction parameters on the morphology and structure of the CuNWs,obtained the optimum fabrication conditions of CuNWs,and successfully prepared the well-dispersed CuNWs with high aspect ratio.Finally,we used the CuNWs dispersed in hexane to fabricate the transparent conductive films.The thesis can be summarized as the following three points:?1?By wet chemical method with oleyamine as the reducing agent,structure-directing agent and solvent,CuCl2·2H2O as a source of copper,Ni?acac?2 as catalytic agent,we successfully prepared the CuNWs.We examined the microstructure of the samples at different reaction times by the scanning electron microscopy?SEM?and the X-ray diffraction?XRD?.These results indicated that the CuNWs were originated from nanocrystals,through a one to one self-assembling route between the initial seeds.The nanowires were found to be single-crystalline and the growth direction of these wires was along[11^—0]concluded from the selected area electron diffraction?SAED?pattern and high-resolution TEM images.?2?The effects of different reaction conditions on the morphology and component of the CuNWs were studied from four aspects respectively:the volume of oleyamine,the amount of Ni?acac?₂,the reaction temperature,and the copper precursors.Thus the optimum reaction condition found as follows:the amount of Ni?acac?2 is 250 mg,the amount of CuCl2·2H2O is 200 mg,the volume of oleyamine is 10 mL,and the reaction temperature is 170?.Under the conditions,the CuNWs with well-dispersed and high aspect ratio?length of 15-40?m,diameter about 20-40 nm?were obtained.In addition,it has been proved that the Cl^-is attached onto the?200?facets selectively and Cu²⁺ions are strongly coordinated by Cl^-,which plays an important role in the formation process of copper nanowires.?3?The prepared CuNWs were dispersed in hexane and then coated as transparent conductive films on the glass substrate.The effect of the annealing temperature on the optical and electrical properties of the films was studied.It was found that the transparent conductive films had the best performance when the annealing temperature was 300?.In addition,the properties of transparent conductive films prepared by CuNWs with larger aspect ratio are better than that with a small aspect ratio.We also drew the conclusion that the transparency of conductive film was inversely proportional to the conductivity.The transparent electrodes fabricated using the CuNWs achieved a high transparency of 82%with a resistance of 42±5?/?.