On the materials level, the performance of thermoelectric (TE) devices can be defined by the thermoelectric figure of merit (zT). This, however, does not provide a complete picture due to the complex interplay between electronic and thermal transport properties and the uncertain thermal impedance matching between external and internal thermal resistances in different realistic thermal circumstances. Appropriate design of individual material properties and geometry parameters considering the realistic thermal circumstance can greatly enhance the device-level performance of TE devices. In this work, we develop a framework to clarify such interactions in thermoelectric coolers (TEC) with a newly proposed q-h characteristic curve, which can be used to identify how a TEC design is of effectiveness for a specific realistic thermal circumstance. The effects of zT, the individual TE material properties (i.e., thermal conductivity k, electrical conductivity σ and Seebeck coefficient S) as well as the geometry parameters (i.e., pillar height and filling factor) on the q-h characteristic curve are theoretically and experimentally investigated, respectively. TEC modules with higher zT, short pillars and high filling factor show stronger capability to handle high heat flux load, especially for the cases with high heat dissipation coefficient at hot side. The thermal property (k) and electrical properties (σ and S) are responsible for the low heat flux load (e.g., wearable TEC) and high heat flux load (e.g., on-chip TEC cooling), respectively. For wearable TEC, increasing the internal thermal resistance can prevent the back flow heat, which can be achieved with tall pillars, low filling factor and optimizing zT towards lowering thermal conductivity k. For on-chip TEC cooling, reducing the Joule heating and increasing the thermoelectric effect become dominant factors in lowering the code-side temperature of TEC modules. This can be achieved with short pillars, high filling factor and optimizing zT towards increasing the power factor S2σ. This work provides significant insights into the complex interplay between material-level properties, device-level parameters and the external thermal circumstance in determining the performance of TEC devices. The results enable researchers to design optimal TEC devices for realistic applications with different boundary conditions.

中文翻译：

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现实热环境下热电冷却器应用的新颖特性曲线：理论与实验


在材料层面，热电（TE）器件的性能可以通过热电品质因数（zT）来定义。然而，由于电子和热传输特性之间复杂的相互作用以及不同实际热环境下外部和内部热阻之间的不确定热阻抗匹配，这并不能提供完整的情况。考虑到实际热环境，对各个材料属性和几何参数进行适当设计可以极大地提高 TE 器件的器件级性能。在这项工作中，我们开发了一个框架，通过新提出的 qh 特性曲线来阐明热电冷却器 (TEC) 中的这种相互作用，该曲线可用于确定 TEC 设计对于特定的实际热环境的有效性。从理论上和实验上研究了 zT、单个 TE 材料特性（即导热系数 k、导电系数 σ 和塞贝克系数 S）以及几何参数（即柱高度和填充系数）对 qh 特性曲线的影响， 分别。具有更高zT、短柱和高填充因子的TEC模块表现出更强的处理高热流负载的能力，特别是对于热侧散热系数高的情况。热属性 (k) 和电属性（σ 和 S）分别决定低热通量负载（例如，可穿戴 TEC）和高热通量负载（例如，片上 TEC 冷却）。对于可穿戴TEC，增加内部热阻可以防止热量回流，这可以通过高柱、低填充因子和优化zT以降低导热系数k来实现。 对于片上TEC冷却，减少焦耳热和增加热电效应成为降低TEC模块代码端温度的主导因素。这可以通过短柱、高填充因数和优化 zT 以提高功率因数 S2σ 来实现。这项工作为材料级特性、器件级参数和外部热环境之间复杂的相互作用提供了重要的见解，以确定 TEC 器件的性能。研究结果使研究人员能够为具有不同边界条件的实际应用设计最佳的 TEC 器件。