Transverse thermoelectric materials: Recent advances and challenges

Transverse thermoelectricity (TTE) based on the Nernst effect has proven to be an alternative solution for the energy harvesting from environments, in contract to the classic longitudinal thermoelectric materials based on the Seebeck effect. The past years have witnessed significant progress both in exploring materials and adaption performance boosting strategies. Most of the reported TTE materials belong to the category of topological semimetal with high carrier mobility, which is very different from the classic thermoelectric semiconductors. This review presents the recent advances in the new TTE materials and performance enhancement strategies. The state-of-the-art TTE materials were classified into the Dirac-type, Weyl-type, and Nodal-line type according to their unique topological characters. The strategies for boosting the TTE performance, including defect engineering and topological phase transition, are systematically reviewed. Besides, the architectures of the TTE power generation devices are discussed, with a special attention on the challenge to achieve high energy conversion efficiency. Finally, the related challenges for further development both in TTE materials and devices are discussed, shining a light on the understanding of various emergent physical mechanisms.