Catalonia Institute for Energy Research - IREC, 08930 Sant Adrià de Besòs, Barcelona, Spain.
Chem Soc Rev. 2017 Jun 19;46(12):3510-3528. doi: 10.1039/c6cs00567e.
The conversion of thermal energy to electricity and vice versa by means of solid state thermoelectric devices is extremely appealing. However, its cost-effectiveness is seriously hampered by the relatively high production cost and low efficiency of current thermoelectric materials and devices. To overcome present challenges and enable a successful deployment of thermoelectric systems in their wide application range, materials with significantly improved performance need to be developed. Nanostructuration can help in several ways to reach the very particular group of properties required to achieve high thermoelectric performances. Nanodomains inserted within a crystalline matrix can provide large charge carrier concentrations without strongly influencing their mobility, thus allowing to reach very high electrical conductivities. Nanostructured materials contain numerous grain boundaries that efficiently scatter mid- and long-wavelength phonons thus reducing the thermal conductivity. Furthermore, nanocrystalline domains can enhance the Seebeck coefficient by modifying the density of states and/or providing type- and energy-dependent charge carrier scattering. All these advantages can only be reached when engineering a complex type of material, nanocomposites, with exquisite control over structural and chemical parameters at multiple length scales. Since current conventional nanomaterial production technologies lack such level of control, alternative strategies need to be developed and adjusted to the specifics of the field. A particularly suitable approach to produce nanocomposites with unique level of control over their structural and compositional parameters is their bottom-up engineering from solution-processed nanoparticles. In this work, we review the state-of-the-art of this technology applied to the thermoelectric field, including the synthesis of nanoparticles of suitable materials with precisely engineered composition and surface chemistry, their combination and consolidation into nanostructured materials, the strategies to electronically dope such materials and the attempts to fabricate thermoelectric devices using nanoparticle-based nanopowders and inks.
通过固态热电设备将热能转换为电能，反之亦然，这极具吸引力。然而，当前热电材料和设备的制造成本高、效率低，严重阻碍了其成本效益。为了克服当前的挑战，并使热电系统在其广泛的应用范围内成功部署，需要开发具有显著改进性能的材料。纳米结构化可以通过多种方式帮助达到实现高热电性能所需的非常特殊的性能组。纳米域插入晶体基质中可以提供大的载流子浓度，而不会强烈影响其迁移率，从而可以达到非常高的电导率。纳米结构材料包含许多晶界，这些晶界可以有效地散射中长波长声子，从而降低热导率。此外，纳米晶畴可以通过改变态密度和/或提供与类型和能量相关的载流子散射来增强塞贝克系数。只有当设计出一种具有复杂类型的材料——纳米复合材料时，才能获得所有这些优势，这种材料对多个长度尺度的结构和化学参数具有精细的控制。由于当前的常规纳米材料生产技术缺乏这种水平的控制，因此需要开发替代策略，并使其适应该领域的具体情况。一种特别适合于对结构和组成参数进行独特控制的纳米复合材料的方法是从溶液处理的纳米颗粒自上而下地进行工程设计。在这项工作中，我们综述了将这种技术应用于热电领域的最新进展，包括合成具有精确设计的组成和表面化学的合适材料的纳米颗粒、将它们组合并固结为纳米结构材料、对这些材料进行电子掺杂的策略，以及尝试使用基于纳米颗粒的纳米粉末和油墨制造热电器件。
