Evolving Strategies Toward Seebeck Coefficient Enhancement

ConspectusThermoelectric (TE) materials, interconverting electrical energy with heat energy, could improve energy utilization efficiency, optimize the energy structure, and promote sustainable economic and social development. The Seebeck coefficient (S), characterizing the output power, is a particularly important parameter for conversion efficiency of TE materials. In the past 200 years since the Seebeck effect was discovered, researchers have tried various ways to increase S to increase the TE performance of materials. In addition to traditional TE approaches to enhance the S, such as energy filtering effect and band convergence, innovative methods of improving the generalized S have emerged in interdisciplinary disciplines, like spin entropy.We have successfully optimized the S to boost the performance of many TE materials, such as SnTe, SnSe, and SnS. In this Account, we focus on the physical mechanisms affecting the S, discuss traditional and innovative methods to optimize the S, and look forward to some promising interdisciplinary approaches for further research to improve the S. First, we analyze the physical mechanism of the basic parameters and their effects on S. Optimizing the carrier concentration, the adjustment of scattering behavior and the increment of effective mass are common methods of improving the S. Second, we summarize several emerging interdisciplinary methods that could enhance the generalized S, like the spin caloritronic effect including magnon/paramagnon drag, spin entropy, and spin fluctuation. The spin Seebeck effect liberates the traditional direction limit between temperature and S and gives a new path toward the S enhancement. We also emphasize the significance of the utilization of phonon drag in the low temperature area. Third, based on previous work, we think the topological states regulation is a burgeoning innovative method for S enhancement of TE materials. Last, we discuss and envision some interdisciplinary strategies for further improving S in the future. This Account indicates that S could be regulated as required, and the interdisciplinary research is beneficial to expand the methods of optimizing TE parameters. We hope to draw the attention of researchers to the enhancement of S and TE performance via innovative study and guide researchers to promote the theoretical innovation research of TE materials.