Anomalously Large Seebeck Coefficient of CuFeS2 Derives from Large Asymmetry in the Energy Dependence of Carrier Relaxation Time

• Published in: Chemistry of materials 2020-03, Vol.32 (6), p.2639-2646
• Main Authors: Xie, Hongyao, Su, Xianli, Bailey, Trevor P, Zhang, Cheng, Liu, Wei, Uher, Ctirad, Tang, Xinfeng, Kanatzidis, Mercouri G
• Format: Article
• Language: English
• Subjects: Carrier dynamics; Electrical conductivity; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Mobility; Scattering; Thermodynamic modeling
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.0c00388

The Seebeck effect in a material originates from the distribution of asymmetry in the electron transport under a temperature gradient, which has contributions from the energy-dependent electronic density-of-states and carrier mobility. However, because the energy dependence of common electron scattering mechanisms is weak, the mobility-driven Seebeck coefficient has long been ignored in most thermoelectric materials, and the energy asymmetry of the density-of-states has been considered the dominant contribution. In this work, we describe a hopping transport behavior observed in CuFeS2, and a large carrier Hall mobility gradient of dμH/dT that creates an unusually large energy-dependent mobility contribution to the Seebeck coefficient. This work offers several ideas regarding the mobility-driven Seebeck effect and its potential utilization in the design of thermoelectric materials.