ABSTRACT

The efficiency of a thermoelectric generator and the coefficient of performance (COP) of a thermoelectric heat pump are related to the hot and cold junction temperatures and a quantity known as the figure of merit, zT. During the second half of the twentieth century the figure of merit has gradually improved. This has come about through the selection of semiconducting materials with improved electronic properties and a small lattice thermal conductivity. Further advancements have been achieved by enhancing the scattering of phonons. There is also the possibility of improving the so-called power factor, that is the part of the figure of merit that contains the Seebeck coefficient and the electrical conductivity. However, it appears that it will be increasingly difficult to make further advances because of the manner in which these quantities vary with the Fermi energy. It is shown that this may set a practical limit on zT. Nevertheless, it may be possible to reach an efficiency or COP of about 40% of that of an ideal thermodynamic machine.

摘要

热电发电机的效率和热电热泵的性能系数（COP）与热结点和冷结点的温度以及一个称为品质因数zT的量有关。。在二十世纪下半叶，功绩逐渐提高。这是通过选择具有改善的电子性能和较小的晶格热导率的半导体材料实现的。通过增强声子的散射已经取得了进一步的进步。也有可能改善所谓的功率因数，即功率因数中包含塞贝克系数和电导率的部分。但是，由于这些量随费米能量的变化方式而变得越来越困难，因此似乎很难取得进一步的进展。结果表明，这可能对zT设置了实际限制。然而，可能有可能达到理想热力学机器效率或COP的40％左右。