碲化铋基热电器件的结构设计与性能优化研究

STRUCTURAL DESIGN AND PERFORMANCE OPTIMIZATION OF BISMUTH TELLURIDE BASED THERMOELECTRIC DEVICES

郭足腾

11849352

硕士

材料工程

何佳清

2020-05-28

2020-07-15

哈尔滨工业大学

深圳

目前，传统化石能源的持续开采与使用所带来的的能源危机与环境污染严重影响着人类社会的可持续发展。由此，开发出一种环境友好的新型清洁能源已成为人类亟须共同解决的问题。热电转换技术可以将耗散在人类活动中的余热废热，通过泽贝克（Seebeck）效应直接转换为电能；相反地，通过佩尔捷（Peltier）效应也能将电能转换为热量的吸收与释放。碲化铋（Bi2Te3）基热电材料由于其最佳热电性能工作温度区间处于室温附近，因此常被用作室温附近发电与制冷的热电材料，也是目前市场上最为广泛商业化运用的一种热电材料体系。在本论文中，通过热压和拉晶的方式分别制备了p型碲化铋基热电材料BiSbTe及n型碲化铋基材料BiTeSe，其最大热电优值ZT分别可达到1.1与0.9。采用陶瓷基板将24对所制备的p型与n型碲化铋基热电臂制备成尺寸为25 mm×19 mm×2.38 mm的平板式热电器件，在130℃的温度梯度（高温160℃，低温30℃）测试下，其最大输出功率可达到0.46 W，最大热电转换效率接近5.56%。近年来，随着物联网与柔性电子器件的发展，市场对清洁环保、寿命长、稳定高、可弯折性的分布式自供能电源提出了迫切需求，柔性热电器件可以通过将它们顺应热源表面形貌地附着在热源上，直接将热量转化为电能，而持续受到越来越多的关注。传统的无机热电材料制备的热电器件通常为以陶瓷片为基板的平板式热电器件，以保持器件使用的高机械性能及稳定性。与无机块体热电材料相比，常见柔性器件通常采用各类有机热电材料，其热电性能都远低于无机块体材料。本论文中通过将数学上的几何算法合理地引入到无机块体材料的平板式热电器件，完成了无机材料柔性热电器件的设计，实现了一种高性能的柔性无机热电器件（f-TED）的制备。通过将人工裂缝与所选定的基板切割方式相结合，实现无机热电器件的全柔性设计，并且器件的弯曲角度可为0 ~ 360度之间的任意角度。此外，该种柔性无机热电器件的设计与制备方式引入的接触电阻较低。论文中通过实验测量和数值模拟以及接触电阻模型，表明并验证f-TED在不同温差和人工裂缝下都能表现出高的能量转换效率和输出功率。值得注意的是，对于能进行360°全柔性弯曲的碲化铋基f-TED，在接近室温（53 K温差）的情况下，其归一化最大功率密度为19.6 mW/cm2，热电转换效率约为3%。这些结果为将f-TED用于具有不同表面曲率的热源或散热器的能量产生和热管理提供了可行性，尤其是应用在自供电的可穿戴机电一体化设备和物联网（IoT）中的柔性芯片冷却过程中。

To date, the increasing energy consumption of chemical fuels around the world results in energy crisis and environmental pollution. Thus, the alternative utilization of eco-friendly and renewable clean energy resources has become a critical solution for sustainable development of society and economic growth. The thermoelectric conversion technology can directly convert the waste heat dissipated from human activities into electricity through the Seebeck effect of thermoelectric materials. Reversely, the Peltier effect can also transfer input electricity into heat absorption and release. Currently, the market diversification has put forward urgent demands for clean energy, durable and stable power supplies, high power electronic devices, and flexible electronics. Flexible electronics and thermoelectric devices can be integrated by conforming onto the surface morphology of the environmental heat source. The waste heat from the heat source can be directly harvested into electricity by flexible thermoelectrics. Consequently, the flexible thermoelectrics attracted tremendous attention in recent years. Owing to the performance matching at room-temperature, Bi2Te3-based thermoelectric materials have been widely used for power generation and refrigeration near room temperature in academy and industry. From a view of materials engineering, the p-type material BiSbTe and the n-type material BiTeSe were fabricated by hot-pressing and crystal-pulling, respectively. The maximum thermoelectric figure of merit ZT is around 1.1 and 0.9, respectively. Ceramic substrates are used to fabricate the flat thermoelectric devices with 24 pairs of p- and n-type Bi2Te3-based thermoelectric legs. The dimension of the device is 25 mm × 19 mm × 2.38 mm and the maximum output power of 0.46 W, as well as energy conversion efficiency of 5.56% are achieved under 130 K temperature difference.In terms of flexible thermoelectrics, conventional approaches are mainly focused inorganic thermoelectric materials, and the devices are fabricated with flat-plate ceramic substrates to maintain the high mechanical performance and stability. However, there is an increasing demand for flexible and wearable electronic devices in daily life and industrial applications, which also promotes continuous research and development of flexible thermoelectrics. Compared with inorganic bulk thermoelectric materials, the thermoelectric performance of typical flexible thermoelecric materials are relatively poorer than that of inorganic bulk materials.In this work, the mathematical geometry algorithm is rationally introduced into flat-to-flexible device design and optimization of flexible thermoelectrics with inorganic thermoelectric materials. This flexible thermolectric devices (f-TED) have both high thermoelectric performance and high flexibility. Inspired by the cyclotomic rule, artificial cracks and selected substrate cutting methods are utilized, a fully flexible inorganic thermoelectric device with bending angle from 0 to 360 degrees is achieved. In addition, the interfacial metal-semiconductorcontact behavior is design and fabrication method of the flexible inorganic thermoelectric device introduces low contact resistance. Based uponexperimental measurement, numerical simulation and contact resistance model analysis in this work, the energy conversion efficiency and output power under various temperature differences and artificial cracks are investigated. Noticeably, the bismuth telluride-based f-TED with a 360-degree full flexible bending can generate normalized maximum power density of 19.6 mW/cm2 and the power conversion efficiency of 3% under 53 K temperature difference (near room temperature). These results provide the feasibility of using f-TED for energy generation and thermal management of heat sources or heat sinks with different surface curvatures, especially in self-powered wearable mechatronic devices and flexible chip cooling in the Internet of Things (IoT).

热电器件 碲化铋 柔性电子 数学算法 能量转换

thermoelectric devices bismuth telluride flexible electronics mathematical algorithm power conversion

中文

联合培养

南方科技大学

郭足腾. 碲化铋基热电器件的结构设计与性能优化研究[D]. 深圳. 哈尔滨工业大学,2020.