NSF/DOE Thermoelectrics Partnership: INORGANIC-ORGANIC HYBRID THERMOELECTRICS

1048702VaddirajuIntellectual Merit：该提案使用固态热电模块将汽车废热直接转化为清洁电力，而不会产生额外的温室气体排放。合适的热电器件要求：1)高转换效率，2)优化的外形因素，3)高稳定性，以及4)优化系统设计的可调性。为了在汽车中广泛使用热电模块，需要zT3，这是目前最先进的设备无法实现的。最近的理论预测表明，一维纳米结构（纳米线）对于制造高效热电模块是有用的。制造具有zT3性能的热电器件和模块需要回答两个首要问题：Q1)实现zT3性能所需的无机纳米线的尺寸和化学成分是什么？如何将这些纳米线大规模集成到热电器件和模块中？这个提议吗?s的假设是，可以通过“开箱即用”的方法制造具有zT3的热电器件。利用有机和无机材料一致的方法，通过均质？分子连接?无机纳米线相互连接或异质布线？有机半导体薄膜。这两种方法有望解决难以捉摸的纳米材料大规模集成问题，同时也为明智选择高热电性能的化学成分提供必要的灵活性。在大型（1英寸2）无机-有机杂化TE器件中展示zT3性能的最终目标将通过以下方式实现：1)使用众所周知的化学气相沉积技术，对该应用进行改进，合成无机纳米线和有机薄膜，然后使用？分子连接?细胞的大小从几平方厘米到几平方厘米不等。2)系统研究了无机纳米线尺寸和有机导电聚合物薄膜化学性质和厚度对各自热电性能的影响，以及它们作为？分子连接?无机混合动力车。被提议者提供的第二个好处是什么？分子连接?组件增强了抗空气和湿气辅助降解以及抗高温降解的稳定性。这是由于杂交体中所有悬空键的饱和，没有留下氧气/水分吸附和反应的空间。悬空键的完全饱和也有望使杂化物在高温下保持稳定。高达800摄氏度的温差可用于汽车发电。因此，在25-800℃的宽温度范围内，将对混合材料的热电性能进行系统的研究，以评估在该温度范围内可以实现稳定的zT3性能。最后，将单个TE器件组装成模块需要一种金属，这种金属在与TE电池接触时表现出低电荷转移阻力。因此，建议研究的最后一个方面是确定在不降低其性能的情况下将单个TE器件组装成TE模块所需的金属类型。系统地研究金属杂化结的接触电阻将通过改变与杂化接触的金属材料（使用传递长度法）来进行。将推断出将单个TE器件组装成具有zT3性能的模块所需的金属类型。更广泛的影响：拟议工作的教育影响将是通过各种途径培训高中生，本科生和研究生。1) PI与和谐科学学院副校长Berkan kaya先生合作，提议培训德克萨斯州休斯顿和谐科学学院的高中生，教授他们纳米材料合成和表征技术。将设计旨在制造能量转换装置的小型项目，他们的工作成果将在各种科学展览和竞赛中展出，例如？国际可持续发展世界（工程，环境，能源）（www.isweeep.org）。2) PI也是NASA的志愿者？（五）科技大学生激励计划（http://mustmentor.org）。通过这一途径，PI建议招收本科生，并对他们进行热电制造技术的培训，并进一步激励他们进行研究生教育。对研究生的培训将包括开发一门对许多学科的学生都有用的新课程。这门暂定于2011年春季开设的课程名为？用于能量转换的纳米材料？

1048702VaddirajuIntellectual Merit: The proposal uses solid-state thermoelectric modules to convert automobile waste heat directly into clean electricity without contributing additional greenhouse gas emissions. Suitable thermoelectric devices require: 1) high conversion efficiencies, 2) optimized form factor, 3) high stability, and 4) tunability for optimized system design. For widespread use of thermoelectric modules in automobiles, a zT3 is needed, which is not possible with the current state-of-the-art devices. Recent theoretical predictions indicate that one-dimensional nanostructures (nanowires) are useful for the fabrication of highly efficient thermoelectric modules. Fabrication of thermoelectric devices and modules with zT3 performance requires answering two overarching questions: Q1) what are the sizes and chemical compositions of inorganic nanowires required for achieving zT3 performance? Q2) how can these nanowires be integrated on a large-scale into thermoelectric devices and modules? This proposal?s hypothesis is that thermoelectric devices with zT3 can be fabricated through an ?out-of-the-box? approach that utilizes organic and inorganic materials in unison, performed through homogeneous ?molecular wiring? of inorganic nanowires either to each other or though heterogeneous ?wiring? to organic semiconductor thin films. These two approaches are expected to solve the elusive problem of large-scale integration of nanomaterials while also providing the necessary flexibility for judicious selection of both the chemical components for high thermoelectric performance. The final goal of demonstrating zT3 performance in large ( 1inch2) inorganic-organic hybrid TE devices will be realized by: 1) Using well-known chemical vapor deposition techniques, modified to this application, to synthesize both inorganic nanowires and organic thin films, followed by assembling them using ?molecular wiring? into cells of various sizes ranging from a few nm2 to a few cm2. 2) Systematically studying the effect of inorganic nanowire size and organic conducting polymer thin film chemistry and thickness on their individual thermoelectric performance, and also on their performance when used in unison as ?molecular wired? inorganic-organic hybrids.A second advantage offered by the proposed ?molecular wired? assemblies is enhanced stability against air and moisture-assisted degradation and also against high temperature degradation. This is owed to the saturation of all dangling bonds in the hybrids, leaving no room for both oxygen/moisture adsorption and reaction. This complete saturation of dangling bonds is also expected to make the hybrids stable at very high temperatures. A large temperature difference, as high as 800oC, is available for electricity generation in automobiles. Hence, systematic investigation of the thermoelectric performance of the hybrids over a wide temperature range of 25-800oC will be performed to evaluate the temperature range over which stable zT3 performance could be realized in them.Finally, assembling individual TE devices into modules requires a metal that exhibits low resistance to charge transfer when brought into contact with the TE cells. Hence, the last aspect of the proposed study is to determine the type of the metal required for assembling individual TE devices into TE modules without lowering their performance.Systematic studies of the contact resistance of metal-hybrid junctions will be performed by varying the material of the metal in contact with the hybrids (using transfer length method). The type of the metal required for assembling individual TE devices into modules exhibiting zT3 performance will be deduced.Broader Impact: The educational impact of the proposed work will be the training of high school, undergraduate and graduate students through various avenues. 1) The PI, in collaboration with Mr. Berkan kaya, Assistant Principal at Harmony Science Academy, proposes to train high school students from Harmony Science Academy in Houston, TX and teach them techniques of nanomaterials synthesis and characterization. Small projects aimed at fabrication of energy conversion devices will be designed and the results of their work will be presented at various science fairs and competitions, such as ?International Sustainable World (Engineering, Environment, Energy) (www.isweeep.org). 2) The PI is also a volunteer for the NASA?s Motivating Undergraduates in Science and Technology (http://mustmentor.org) project. Through this avenue, the PI proposes to recruit undergraduate students and train them on the techniques for the fabrication of thermoelectrics and further motivate them to pursue graduate education. 3) Training of graduate students will include development of a new class useful for students across many disciplines. This class tentatively scheduled to be offered in spring 2011 is entitled ?Nanomaterials for Energy Conversion?.