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Low dimensional carbon based organic thermoelectric composites: Synthesis, characterization, and performance.

机译：低维碳基有机热电复合材料：合成，表征和性能。

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摘要

Since the discovery of the most commonly used room temperature thermoelectric material bismuth telluride nearly sixty years ago, the performance of thermoelectrics has seen little improvement. In recent years, slight improvements through the use of complex crystalline structures and nano arrays have renewed interest in thermoelectrics, however, their performance is still orders of magnitude below that required to replace current heat engine power sources. Alternatively, one potential solution is to consider using thermoelectrics in low powered applications where their efficiencies are comparable to those of standard heat engines, and where the use of heat engines is physically impractical.;The use of nonorganic crystalline thermoelectrics like bismuth telluride are also somewhat impractical despite their high performance at lower power output levels due to their fragile and rigid physical structure which limits their application. Carbon nanotube based polymer composites possess several properties that make them ideal for use in low powered waste heat recovery applications not suitable to nonorganic crystalline materials. The favorable thermoelectric properties of the carbon nanotubes with moderate Seebeck coefficients and potentially large electrical conductivities result in modest power factors, while the low thermal conductivity of the polymer host aids in maintaining a temperature gradient across the composite, thus improving the figure of merit. Although the thermoelectric performance of these composites is lower than that of standard crystalline thermoelectrics, their light weight and flexible physical structure makes them more ideal for use in personal and portable electronics that utilize waste heat to maintain a temperature gradient.;In order to effectively utilize a thermoelectric material in a practical application, they must be combined in a device structure consisting of alternating p-type and n-type elements that are connected electrically in series and thermally in parallel. Here, we introduce a novel device architecture suited to using the thin film carbon nanotube based polymer composites. The device performance is then dictated by the intrinsic thermoelectric properties of the individual layers composing the device. Therefore, the majority of the work presented here focuses on understanding the thermoelectric properties of the individual layers. Effects on these properties are quantified including the chemical vapor deposition growth temperature, sonication, acid reflux treatment, temperature, n-type doping through the use of polyethylenimine, and composite composition including carbon nanotube, polymer, and solvent type and concentrations. By quantifying these effects, the thermoelectric performance of the individual layers can be optimized in order to increase the total power output of the device. Ultimately however, the total power output is limited by the specific application; therefore, power output measurements are performed versus several application parameters including the temperature difference, load resistance, dimensions of the device, and the number of repeatable thermocouple elements contained within the device. Finally, the power output of an interconnected device array is measured to exemplify the potential performance of an application appropriate design.
机译：自将近60年前发现最常用的室温热电材料碲化铋以来，热电性能几乎没有改善。近年来，通过使用复杂的晶体结构和纳米阵列的轻微改进已经重新引起了对热电的兴趣，但是，其性能仍然比替换当前的热机电源所需的性能低几个数量级。或者，一种潜在的解决方案是考虑在效率与标准热机相当的低功率应用中使用热电，并且在物理上不可行使用热机。;使用诸如碲化铋的非有机晶体热电也有些尽管由于其脆弱而坚固的物理结构限制了它们的应用，但它们在较低的功率输出水平下却具有高性能，因此不切实际。碳纳米管基聚合物复合材料具有多种性能，使其非常适合不适合非有机晶体材料的低功率余热回收应用。具有适中塞贝克系数和可能较大的电导率的碳纳米管的良好热电性能导致功率因数适中，而聚合物主体的低热导率有助于维持复合材料的温度梯度，从而改善了品质因数。尽管这些复合材料的热电性能低于标准晶体热电性能，但它们的轻质和灵活的物理结构使其更适合用于利用废热来保持温度梯度的个人和便携式电子产品。作为实际应用中的热电材料，必须将它们组合成由交替电串联和热并联连接的交替的p型和n型元件组成的器件结构。在这里，我们介绍一种适合使用基于薄膜碳纳米管的聚合物复合材料的新型器件架构。然后，器件性能由组成器件的各个层的固有热电特性决定。因此，这里提出的大部分工作都集中在理解各个层的热电特性上。量化对这些性质的影响，包括化学气相沉积生长温度，超声处理，酸回流处理，温度，通过使用聚乙烯亚胺的n型掺杂以及包括碳纳米管，聚合物以及溶剂类型和浓度的复合成分。通过量化这些影响，可以优化各个层的热电性能，以增加设备的总功率输出。但是最终，总功率输出受特定应用的限制；因此，将针对几个应用参数进行功率输出测量，包括温度差，负载电阻，设备尺寸以及设备中包含的可重复热电偶元件的数量。最后，对互连设备阵列的功率输出进行测量，以举例说明适合应用的设计的潜在性能。

著录项

  • 作者

    Hewitt, Corey Alan.;

  • 作者单位

    Wake Forest University.;

  • 授予单位 Wake Forest University.;
  • 学科 Nanotechnology.;Engineering Materials Science.;Chemistry Polymer.;Physics General.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 227 p.
  • 总页数 227
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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