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Enhancement of Thermoelectric Properties of ALD Synthesized PbTe And PbSe by Phonon Engineering

机译：声子工程技术增强ALD合成PbTe和PbSe的热电性能

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摘要

Thermoelectrics is a green renewable energy technology that plays an important role in power generation due to its potential in generating electricity out of waste heat. The main challenge for the development of thermoelectrics is its low conversion efficiency. One key strategy to improve conversion efficiency is focused on reducing the thermal conductivity of thermoelectric materials. In this thesis, the novel phononic engineering concept was implemented by conformal ALD deposition of PbTe, PbSe thermoelectric films, and PbTe/PbSe nanolaminates on patterned silicon substrates in order to improve the thermoelectric performance of the thermoelectric films. The silicon substrates were lithographically patterned with a mask into porous templates with a regular or staggered pore arrangement and alternatively into stripe and trench patterns. The effect of nano-patterning on the Seebeck coefficient, electrical conductivity, and thermal conductivity of the thermoelectric films was studied experimentally. The results indicate that usage of porous Si templates simultaneously enhances the Seebeck coefficient and reduces thermal conductivity. A ZT enhancement was acheieved in porous ALD PbTe/PbSe nanolaminates by a factor of up to three at a temperature of 500 K. Therefore, the novel concept and engineering approach of phonon engineering has been successfully rendered. For the case of stripe patterning nano-structures, the simulation results indicate a ZT enhancement was expected in the structures with a mesa stripe width of less than 2 microm and a trench depth larger than 500 nm. For in-plane ZT characterization, a lab-on-a-chip based platform was applied to measure the in-plane Seebeck coefficient, electrical conductivity and thermal conductivity quasi-simultaneously. All of the ALD PbTe and PbSe thin film samples exhibit super low in-plane thermal conductivity kappa, which is attributed to grain boundary scattering occurring in polycrystalline ALD PbTe and PbSe films. In addition, we extended our investigation to the thermoelectric properties of hybrid Surface Anchored Metal-Organic-Framework (SURMOF) thin films. TCNQ loaded MOF films exhibit a higher Seebeck coefficient and super low thermal conductivity kappa in the temperature range of 290 ∼ 350 K, which render MOF films a promising thermoelectric material for thermoelectric applications around room temperature and a potentially inexpensive alternative hybrid organic-inorganic thermoelectric materials.
机译：热电是一种绿色可再生能源技术，由于其具有利用余热发电的潜力，因此在发电中起着重要作用。热电学发展的主要挑战是其低转换效率。提高转化效率的一项关键策略集中在降低热电材料的导热系数上。本文通过在图案化硅基板上共形沉积PbTe，PbSe热电薄膜和PbTe / PbSe纳米叠层的ALD技术，实现了新的声子工程学概念，以提高热电薄膜的热电性能。用掩模将硅基板光刻图案化成具有规则或交错的孔排列的多孔模板，或者交替地形成条纹和沟槽图案。实验研究了纳米构图对热电薄膜塞贝克系数，电导率和热导率的影响。结果表明，使用多孔硅模板可同时提高塞贝克系数并降低热导率。在500 K的温度下，多孔ALD PbTe / PbSe纳米层合物的ZT增强达到了三倍。因此，声子工程学的新颖概念和工程方法已经成功地提出。对于条纹图案化纳米结构的情况，仿真结果表明，在台面条纹宽度小于2微米且沟槽深度大于500 nm的结构中，预期ZT增强。为了进行平面ZT表征，采用了基于芯片实验室的平台来同时测量平面塞贝克系数，电导率和热导率。所有的ALD PbTe和PbSe薄膜样品均显示出超低的面内导热系数kappa，这归因于多晶ALD PbTe和PbSe薄膜中发生的晶界散射。此外，我们将研究扩展到混合表面锚固金属有机框架（SURMOF）薄膜的热电性能。负载TCNQ的MOF薄膜在290〜350 K的温度范围内表现出更高的塞贝克系数和超低导热系数kappa，这使得MOF薄膜成为一种有前景的热电材料，可用于室温附近的热电应用，并且可能是廉价的替代有机-无机混合热电材料。

著录项

  • 作者

    Chen, Xin.;

  • 作者单位

    Old Dominion University.;

  • 授予单位 Old Dominion University.;
  • 学科 Electrical engineering.;Nanotechnology.
  • 学位 Ph.D.
  • 年度 2017
  • 页码 136 p.
  • 总页数 136
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 古生物学;
  • 关键词

  • 入库时间 2022-08-17 11:38:27

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