期刊
ADVANCED ENERGY MATERIALS
卷 11, 期 28, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/aenm.202101122
关键词
chemical bond weakening; Heikes' equation; SnTe; thermoelectrics
类别
资金
- Japan Society for the Promotion of Science (JSPS) [P19720]
- JSPS KAKENHI [19F19720, JP16H06441]
- ANR [ANR-18-CE05-0037]
- JST-Mirai [JPMJMI19A1]
- NIMS-ICGP program
- Grants-in-Aid for Scientific Research [19F19720] Funding Source: KAKEN
The study explores the use of new dopants to improve the thermoelectric performance of SnTe-based materials, reducing the need for a large temperature gradient. The enhanced performance is mainly attributed to improved weighted mobility, coupling of charge carriers with magnetic entropy, and weakening of chemical bonds.
Most of the best known SnTe-based materials exhibit an attractive thermoelectric figure of merit (zT) only at the high-temperature regime, but their performance at the low-mid temperature ranges is quite uninspiring, and this discordance necessitates a large temperature gradient ( increment T >= 550 K) to effectuate a reasonable efficiency, eta. Here, the transition elements, Ti and Zr, that have not been used in the past are tried as dopants for SnTe and an enhanced device/average zT and/or eta are reported with a lower increment T approximate to 400 K and without the requisite for a stupendous peak/maximum zT. This notable performance emanates from-i) improved weighted mobility by optimally balancing between effective mass, carrier concentration, and mobility, ii) coupling of charge carriers with magnetic entropy, and the paramount factor being the iii) weakening of the chemical bonds (lattice softening). The thermal damping caused by lattice softening affects the phonon group velocity and the elastic properties, and the resultant increase in the degree of anharmonicity and the high density of internal strain-fields, along with the phonon scattering effects, play an active role in tuning the overall thermoelectric performance. This work also excavates/opens up the discussion of applying the Heikes' equation to qualitatively compare the trend of charge carriers for a given thermoelectric material system.
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