Flexible electrodes are prepared by deposition on polyethylene naphthalate substrates, which melt at elevated temperatures, and are, therefore, generally unsuitable for deposition at high temperatures. However, only limited improvement in the conductivity can be achieved for Al-doped ZnO (AZO) films formed at low temperatures. Multilayer transparent conductive films (AZO/Ag/AZO), in which a conductive metal such as Ag is sandwiched between AZO, exhibit superior resistivity and electrical stability against bending compared to AZO films and have attracted considerable attention. In this study, AZO transparent conducting films were investigated as alternatives to indium tin oxide. The electrical characteristics of AZO/Ag/AZO films are not optimal at low temperatures owing to oxidation of Ag and its diffusion into the AZO layer. We, therefore, developed transparent conductive films with an AZO/Ag/Cu/AZO structure in which an intermediate Cu layer suppresses the oxidation of Ag and inhibits its diffusion into the substrate-side AZO layer, changing the deposition conditions of Cu. The optimal characteristics were obtained at a Cu deposition rate of 0.08 nm/s. A further increase in Cu layer thickness suppresses the oxidation of the Ag layer and its diffusion into the substrate-side AZO layer, thereby improving resistivity. Notably, a 5 nm thick Cu layer exhibited exclusive Cu regions, which further prevented the oxidation of Ag and its diffusion into the substrate side of the AZO layer, with a resistivity of 5.12 × 10⁻⁵Ω cm. This resistivity is comparable to that of existing transparent conducting films used in practical applications; however, the transmittance of the AZO/Ag/Cu/AZO film was reduced owing to the low transparency of Cu.

中文翻译：

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Cu沉积改善柔性AZO/Ag/Cu/AZO透明导电薄膜的电学特性

柔性电极通过沉积在聚萘二甲酸乙二醇酯基底上制备，该基底在高温下熔化，因此通常不适合在高温下沉积。然而，对于在低温下形成的掺铝 ZnO (AZO) 薄膜，只能实现有限的电导率改善。多层透明导电膜（AZO/Ag/AZO）是将 Ag 等导电金属夹在 AZO 之间的结构，与 AZO 膜相比，其电阻率和抗弯曲的电气稳定性更佳，因此备受瞩目。在这项研究中，研究了 AZO 透明导电膜作为氧化铟锡的替代品。由于 Ag 的氧化及其扩散到 AZO 层中，AZO/Ag/AZO 薄膜的电学特性在低温下不是最佳的。因此，我们 开发了具有 AZO/Ag/Cu/AZO 结构的透明导电膜，其中中间 Cu 层抑制 Ag 的氧化并抑制其扩散到基板侧 AZO 层中，从而改变 Cu 的沉积条件。在 0.08 nm/s 的 Cu 沉积速率下获得最佳特性。Cu层厚度的进一步增加抑制了Ag层的氧化及其向衬底侧AZO层中的扩散，从而提高了电阻率。值得注意的是，5 nm 厚的 Cu 层显示出独特的 Cu 区域，进一步防止了 Ag 的氧化及其扩散到 AZO 层的基板侧，电阻率为 5.12 × 10 Cu层厚度的进一步增加抑制了Ag层的氧化及其向衬底侧AZO层中的扩散，从而提高了电阻率。值得注意的是，5 nm 厚的 Cu 层显示出独特的 Cu 区域，进一步防止了 Ag 的氧化及其扩散到 AZO 层的基板侧，电阻率为 5.12 × 10 Cu层厚度的进一步增加抑制了Ag层的氧化及其向衬底侧AZO层中的扩散，从而提高了电阻率。值得注意的是，5 nm 厚的 Cu 层显示出独特的 Cu 区域，进一步防止了 Ag 的氧化及其扩散到 AZO 层的基板侧，电阻率为 5.12 × 10^-5欧姆厘米。该电阻率与实际应用中使用的现有透明导电膜的电阻率相当；然而，由于 Cu 的透明度低，AZO/Ag/Cu/AZO 薄膜的透射率降低。