高性能热电器件设计原理与集成技术关键科学问题研究

The highly expected applications of thermoelectric (TE) power generation for harvesting thermal energy and thermoelectric refrigeration for efficient spot cooling have made increasing demands on the thermoelectric devices with all-round advances including high energy conversion efficiency and power density, excellent service reliability, competitive cost, and less environment impact as well. The present project is focusing on the basic research on design approach and fabrication method as well as the service behavior of TE devices. For realizing high conversion efficiency, the optimization of structural geometry and interfacial microstructure as well as the joining technology is important as developing high ZT materials. Exploring joining method and optimizing interfacial structure to eliminate energy loss is one of the major strategies in TE device fabrication technology. The segment device, containing two or more kinds of TE materials coping with different temperature range, is also a promising approach for obtaining high conversion efficiency, but new challenges are simultaneously raised such as realizing stable bonding between the different TE materials with low interfacial electrical/thermal resistance and low thermal stress caused by the difference of CTEs. The design and fabrication of segment TE device with efficiency higher than 12% is one of the main goals of the present project. Further more, to improve the service behavior, which mainly regards the structural stability and the performance degradation under the harsh environment (such as high temperature and large temperature gradient, electrical field, vibration, oxidation or erosive atmosphere, etc.), besides using the intrinsically stable TE materials, the interfacial structure, sealing and insulating components, and the fabricating process are also among the key technical issues. The service behavior will be studied based on the materials genome innovation (MGI) approach through analyzing the failure defects during the whole operation life.

热电器件是实现高效热电能量转换的核心。工业余热热电发电、环境能量收集、局域高精度温控等重大应用需求对热电器件的转换效率、功率密度、可靠性、制造成本等提出了多样化和苛刻的要求，热电器件的设计与集成技术已成为制约热电技术规模化应用的瓶颈。本项目重点开展高效热电发电器件、低维和柔性热电器件的设计方法与集成制造技术的基础科学问题研究，揭示电／热／力多场耦合下热电器件的能量转换机制和器件拓扑结构对器件性能的影响关系，建立热电器件跨尺度结构优化设计方法；系统开展器件全寿命服役行为研究，通过实验研究与仿真模拟相结合，捕获引发热电器件性能演变与失效的基因单元，建立典型热电器件的全寿命周期失效基元数据库，揭示其在服役过程中的演化规律，建立和发展热电器件全寿命周期内性能预测、寿命预测和可靠性评价方法；重点突破低热阻低电阻异质界面的设计与结合、宽温域多级器件集成等关键技术，实现器件转换效率>12％。

本项目面向热电转换技术的工业应用对热电器件的设计与集成技术提出的重大需求，系统开展了高效热电发电器件、低维和柔性热电器件的设计与集成制造技术的基础研究，揭示了热-力-电多场耦合下热电器件的能量转换机制以及器件结构-性能之间的构效关系，揭示了器件服役行为和服役性能的演化规律，建立了热电器件跨尺度结构优化设计方法与集成技术。.通过本项目研究，建立了热电器件全参数三维仿真模型，器件效率的仿真设计值与实测值的误差小于5%，突破了低能量损耗异质界面的设计与结合、多段结构宽温域器件集成等器件制造关键技术，发展了高转换效率、高功率密度（双高）热电器件设计方法，实现了器件性能的大幅提升，单级和级联器件转换效率分别突破10%和12%，器件功率密度达到3.1W/cm2。项目阐明了热电器件电极界面服役行为的反应-扩散机制，确定了界面和表面服役行为是器件性能衰减的主要因素，并建立了服役性能预测模型；解析了热-力耦合作用下影响热电器件热应力的关键因素，并提出了应力缓解方法。发现了室温塑性半导体材料，获得了系列兼具优异塑形变形能力和较高热电优值的n型与p型热电材料，制备出高性能无机柔性热电器件，归一化功率密度为已报道的柔性热电器件最高值；设计制备了高性能有机薄膜热电材料与器件，Ag2Se/尼龙有机薄膜器件的功率密度为有机热电器件的最高值。.本项目在Energy & Environ. Science、Adv. Energy Mater.、Nature Commun.、Angew. Chem. Int. Ed.、Nature Mater.、Science等期刊上发表论文61篇，获授权专利14项；培养博士研究生15名、硕士研究生12名。