STTR Phase I: Fabrication of Low-Cost and High-Efficiency Thermoelectric Materials

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。这个小型企业技术转移第一阶段项目旨在建立以低成本制造高效率纳米结构热电的可行性。采用模板合成的方法，采用电化学沉积的方法制备CoSb3角钨矿纳米线。模板去除后，一种新的可控表面修饰步骤将应用于纳米线。我们期望这种特殊的表面处理能够在更大程度上降低纳米结构CoSb3的导热性，而不是导电性，因为它们各自的散射长度不同。在不同的制备条件下生长、掺杂和处理纳米结构的CoSb3方突石，然后表征。研究将导致量身定制的纳米线阵列的热电特性。我们将解决其中一些关于尺寸和表面改性的挑战。复杂的纳米级表征将使用电化学技术，x射线衍射，电子显微镜（SEM， TEM， EDS和EELS）和x射线光电子能谱（XPS）进行。通过测量电导率、导热系数和塞贝克系数来研究这些纳米结构的效率与线材尺寸、化学成分和表面粗糙度的关系，以获得最高效率的最佳条件。该技术为大规模制造高效的能量转换热电器件奠定了基础。电化学沉积与表面粗化的独特结合为大批量生产低成本、高效率的热电材料提供了巨大的潜力，这是批量加工技术无法实现的。Skutterudite group（如CoSb3）热电材料用于从不同热源（如炉顶发电机、发动机排气驱动的交流发电机替代品、自供电电器）产生电力，但目前的市场受到效率低的限制。随着ZT的增加，该工艺处理的CoSb3可用于许多工作在中温的功率转换器件；此外，它可以在低温应用中与Bi2Te3竞争。此外，这项技术将加强对纳米结构热电材料的科学和技术理解。迄今为止，大多数关于电沉积热电薄膜和纳米结构的研究都集中在合成上，主要是研究其组成和结构。热电性质的合成和表征之间的不协调差距，即塞贝克系数和热电优值，仅为已发表的作品创造了部分画面。虽然镀层的成分和结构是物理性能的关键指标，但其测量的热电性能最终将决定其在汽车和太阳能热工业的供暖、通风和/或空调（HVAC）中的用途。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This Small Business Technology Transfer Phase I project aims at establishing the feasibility of fabricating high-efficiency nanostructured thermoelectric at low cost. CoSb3 skutterudite nanowires will be grown by electrochemical deposition using template synthesis. After template removal, a novel controlled surface modification step will be applied to nanowires. We expect this particular surface treatment alone to reduce thermal conductivity of nanostructured CoSb3 to a greater degree compared to electrical conductivity due to differences in their respective scattering lengths. Nanostructured CoSb3 skutterudite will be grown, doped and treated under various fabrication conditions, and then characterized. Research will lead to tailored thermoelectric properties of the nanowire arrays. We will address some of these challenges regarding both size and surface modification. Complex nanoscale characterization will be performed using electrochemical techniques, X-ray diffraction, electron microscopy (SEM, TEM, EDS and EELS), and X-ray photoelectron spectroscopy (XPS). Measurements of electrical conductivity, thermal conductivity and Seebeck coefficient will be performed to study the efficiency of these nanostructures as a function of wire size, chemical composition and surface roughness in order to obtain an optimal condition for the highest efficiency. This technology lays the foundation for large-scale fabrication of high efficiency thermoelectric devices for energy conversion. The unique combination of electrochemical deposition and surface roughening has great potential for mass production of low-cost and high-efficiency thermoelectric materials that can not be achieved by bulk processing techniques. Skutterudite group (e. g., CoSb3) thermoelectric materials are used to generate electrical power from different heat sources (e. g., stove top generators, engine exhaust powered alternator replacement, self-powered appliances), but the current market is limited by a low efficiency. With an increased ZT, CoSb3 processed by this technology can be used in many power conversion devices operating at intermediate temperatures; moreover, it may compete with Bi2Te3 for low temperature applications. Additionally, this technology will enhance the scientific and technological understanding of nanostructured thermoelectric materials. To date, most of the work on electrodeposited thermoelectric thin films and nanostructures focuses on synthesis, primarily investigating compositions and structure. A dissonant gap between synthesis and characterization of the thermoelectric properties, namely the Seebeck coefficient and thermoelectric figure of merit, creates only a partial picture for published works. While composition and structure of electrodeposits are crucial indicators of physical properties, their measured thermoelectric performance will ultimately dictate their usefulness in heating, ventilation, and/or air conditioning (HVAC) in to vehicles and solar thermal industry.