透明導電薄膜為許多電子產品內不可或缺之材料，而金屬奈米線由於具低電阻、高光穿透度及高可撓曲之特性，因此蔚為現今透明導電薄膜應用之主要研究，其中，奈米銅線(Copper nanowire, CuNW)即為一常用材料之選擇。但習知CuNW於大氣下易氧化，進而影響其電性表現，為此本研究遂嘗試將還原氧化石墨烯(Reduced graphene oxide, rGO)塗佈於CuNW薄膜上以作為隔絕空氣的保護層，並探討不同rGO製備方法對其長時間電性之表現。首先，本研究以還原反應溶液法合成出線徑58 ± 9 nm，線長大於10 μm之CuNW，所製備CuNW的薄膜最佳光電表現為穿透度89.2% @ 550 nm和片電阻22.0 ± 0.6 /sq.。將其置於大氣下15天後，其片電阻飆升至256.7 ± 2.1 /sq.；當時間延長至26天時，其已成為絕緣體。此即凸顯本研究欲改善CuNW於長時間電性穩定表現之必要性。當利用浸塗法塗佈化學還原還原氧化石墨烯(Chemically reduced graphene oxide, c-rGO)於CuNW薄膜上時，由於c-rGO之疏水特性使其無法完整貼附於CuNW表面，故此c-rGO/CuNW複合薄膜之片電阻亦隨暴露大氣時間之增加而飆升。另一方面，如先將氧化石墨烯(Graphene oxide, GO)塗佈於CuNW薄膜上，再於氫氣氣氛中進行熱還原處理(150oC、3 hr)以使之生成氫氣還原氧化石墨烯(Hydrogen reduced graphene oxide, h-rGO)，由於大面積GO可完整服貼於CuNW表面，故經過30天後，h-rGO/CuNW複合薄膜之片電阻從25.1 ± 0.1 /sq.僅略升至42.2 ± 0.1 /sq.，穿透度亦可維持85.9% @ 550 nm。由動態撓曲試驗顯示，h-rGO/CuNW複合薄膜於曲率半徑5.3 mm下連續動態彎曲2500次，其片電阻僅略升0.6 /sq.。基於實驗結果，本研究所研發之h-rGO/CuNW複合薄膜可提供CuNW薄膜於長時間下之穩定電性表現，且兼具高穿透度及高可撓性，於未來光電產業所需透明導電薄膜具極大之應用潛力。

Among the materials for preparing transparent conductive films (TCFs), metal nanowire is gaining a great deal of interest owing to advantages of low sheet resistance (Rsh), high transparency and high flexibility, and copper nanowires (CuNWs) is one of the metal nanowires been investigated. However, CuNWs face the serious problem of oxidation, which results in the deterioration on electrical conductivity. In this work, we developed a highly stable electrical approach based on reduced graphene oxide (rGO)/ CuNW for TCFs. The presence of the rGO playing a role a gas barrier layer can effectively overcome the problem of CuNW oxidation. The electrical stability of the rGO/CuNW films prepared by varied syntheses were investigated systematically. The CuNWs with an average diameter of 58 ± 9 nm and a length longer than 10 μm were synthesized through a solution-based method. The best optoelectrical property of the CuNW film is 89.2% @ 550 nm and 22.0 ± 0.6 Ω/sq. After exposure to ambient atmosphere for 15 days, the Rsh of CuNW film substantially raised to 256.7 ± 2.1 Ω/sq., and became an insulator after 26 days. To solve the oxidation problem, two rGO fabrication processes were developed, one was chemically reduced graphene oxide (c-rGO), and the other was treating the graphene oxide by thermal reduction under hydrogen to form h-rGO. Similar trend of variety in Rsh between c-rGO/CuNW film and CuNW film was detected. On the contrast, after exposure to ambient atmosphere for 30 days, the Rsh of h-rGO/CuNW film was slightly increased from 25.1 ± 0.1 /sq. to 42.2 ± 0.1 /sq. accompanied a transmittance of 85.9% @ 550 nm. Such high electrical stability is due to the complete coverage of h-rGO on CuNW caused by the hydrophilicity of GO in nature. The high flexibilityof h-rGO/CuNW film was also demonstrated. Based upon the obtained results, the synthesized h-rGO/CuNW film possesses high electrical stability and flexibility, which is a potential material in TCFs.

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