Electron and Phonon Transport for Bulk Thermoelectrics, From High-Throughput Screening, Machine Learning Potential, to Electron-Phonon Renormalization

Abstract:
The basic transport properties of thermoelectrics (TEs) are governed by electron and phonon, as well as their interaction. The transport properties have been well-documented for more than half century. Combining with advanced computational tools and materials genome methods, the electron and phonon transport can be applied into many applications, such as screening of new TE materials and understanding of novel transport phenomenon. In Shanghai University, we have established the Materials Hub with Three-Dimensional Structures (MatHub-3d) repository, which serves as the foundation for high-throughput calculations, property analysis, and the design of TE materials. HTP algorithms for transport properties have been developed, and several types of TE materials have been screening. Some of the compounds have been verified experimentally. Furthermore, we utilized a combination of high-throughput computation and machine-learning interatomic potentials (MLIPs) to construct HH130, a standardized database tailored for the 130 half-Heusler compounds in MatHub-3d. A universal force field MACE-HH-v1.0 is also pretrained using the data in HH130. These MLIPs are adopted to studied the phonon transport of complex defective HHs. Electron-phonon renormalization effects of half-Heusler compounds are also studied in a high-throughput manner. Most of the semiconducting half-Heuslers show the Varshni effect, i.e., the band gap decreasing with temperature increase, while 4 entries violate this rule. A favorable band renormalization for TE, which is the band convergence by the temperature, is proposed and realized by experiments.

Bio:
Jiong Yang, graduated from the Shanghai Institute of Ceramics, Chinese Academy of Sciences, and worked as a postdoctoral fellow at the University of Washington in the United States. He is currently a professor and doctoral supervisor at the Materials Genome Institute, Shanghai University. He has long been engaged in material physics related to electron-phonon interaction, thermoelectric material design, and material genome related research. He has won the 2019 International Thermoelectric Society Young Scientist Award for his work on thermoelectric material genes.