Transparent Conductors from Layer-by-Layer Assembled SWNT Films: Importance of Mechanical Properties and a New Figure of Merit
Transparent Conductors from Layer-by-Layer Assembled SWNT Films: Importance of Mechanical Properties and a New Figure of Merit
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DOI：
10.1021/nn100026n
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发表时间：
2010-07-01
期刊：
影响因子：
17.1
通讯作者：
Kotov, Nicholas A.
中科院分区：
文献类型：
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作者：
Shim, Bong Sup;Zhu, Jian;Kotov, Nicholas A.
显示器、传感器、太阳能电池、智能节能窗和柔性电子产品都迫切需要能够取代传统氧化铟锡（ITO）的新型透明导体（TC）。TC的技术要求不仅包括高导电性和透明性，还包括环境稳定性和机械性能，这些在研究环境中经常被忽视。单壁碳纳米管（SWNT）涂层已被建议作为替代TC材料，但通常缺乏足够的耐磨性相比，ITO。平衡电导率、透明度、耐久性和灵活性是一项艰巨的挑战，这促使我们引入了一个新的TC品质因数Pi（TC），它包含了所有这些品质。可以建议将Pi（TC）最大化到ITO或更好的Pi（TC）作为初始研究目标。单壁碳纳米管逐层（LBL）聚合物纳米复合材料结构的微调使得所有必要的性能的集成成为可能。所生产的IC显示出86 Ω/sq的电阻率和80.2%的光学透射率，以及分别为12.3 +/-3.4GPa，218 +/-13MPa和8 +/-1.7J/g的膜的拉伸模量、强度和韧性。还展示了一种新的透明覆盖层，以在恶劣环境中保持这些特性，并具有匹配或更好的强度，韧性和透明度参数。由于应用需求，由LBL制造的TC的弯曲性能特别令人感兴趣，并且超过ITO至少100倍。所生产的涂层的累积品质因数Pi（TC）为0.15 Ω（-1），而常规ITO显示Pi（TC）< 0.07 Ω（-1）。凭借与ITO相当的整体电学和光学性能以及优异的机械性能，所述涂层可以提供ITO或其他基于纳米线和纳米管的TC的优异替代品，特别是在柔性电子器件，显示器和传感器中。
New transparent conductors (TCs) capable of replacing traditional indium tin oxide (ITO) are much needed for displays, sensors, solar cells, smart energy-saving windows, and flexible electronics. Technical requirements of TCs include not only high electrical conductivity and transparency but also environmental stability and mechanical property which are often overlooked in the research environment. Single-walled carbon nanotube (SWNT) coatings have been suggested as alternative TC materials but typically lack sufficient wear resistance compared to ITO. Balancing conductance, transparency, durability, and flexibility is a formidable challenge, which leads us to the introduction of a new TC figure of merit, Pi(TC), incorporating all these qualities. Maximization of Pi(TC) to that of ITO or better can be suggested as an initial research goal. Fine tuning of SWNT layer-by-layer (LBL) polymeric nanocomposite structures makes possible integration of all the necessary properties. The produced IC demonstrated resistivity of 86 Omega/sq with 80.2% optical transmittance combined with tensile modulus, strength, and toughness of the film of 12.3 +/- 3.4 GPa, 218 +/- 13 MPa, and 8 +/- 1.7 J/g, respectively. A new transparent capping layer to conserve these properties in the hostile environment with matching or better strength, toughness, and transparency parameters was also demonstrated. Due to application demands, bending performance of TC made by LBL was of special interest and exceeded that of ITO by at least 100 times. Cumulative figure of merit Pi(TC) for the produced coatings was 0.15 Omega(-1), whereas the conventional ITO showed Pi(TC) < 0.07 Omega(-1). With overall electrical and optical performance comparable to ITO and exceptional mechanical properties, the described coatings can provide an excellent alternative to ITO or other nanowire- and nanotube-based TC specifically in flexible electronics, displays, and sensors.