Ultralow Thermal Conductivity and Thermoelectric Properties of Rb2Bi8Se13

Songting Cai, Shiqiang Hao, Yubo Luo, Xianli Su, Zhong Zhen Luo, Xiaobing Hu, Christopher Wolverton, Vinayak P. Dravid*, Mercouri G. Kanatzidis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Complex bismuth chalcogenides are narrow band gap semiconductors with intrinsic low thermal conductivity, which exhibit high potential as highly efficient thermoelectric materials. Here, we assess the basic thermoelectric properties of polycrystalline Rb2Bi8Se13 in the temperature range 300-823 K as well as performance-optimizing strategies. We find that the as-made bulk samples are single phase with the monoclinic crystal structure (P21/m) and crystallize in layer morphology. The pristine sample exhibits an exceedingly low lattice thermal conductivity of 0.6-0.46 W·m-1·K-1 at 300-823 K, which derives from strong lattice anharmonicity, large Grüneisen parameters, and low phonon velocities induced by the complex crystal structure with heavy atom Bi and a large unit cell. The Cl doping successfully enhances the carrier concentration in Rb2Bi8Se13 with a negligible impact on the electronic band structure, displaying common doping behaviors. Se vacancy, on the contrary, leads to n-type doping and enhances the effective mass and power factors more significantly. Consequently, a maximum ZT of ∼0.75 at 823 K for the 0.3% Se-vacancy-doped sample is obtained.

Original languageEnglish (US)
Pages (from-to)3561-3569
Number of pages9
JournalChemistry of Materials
Volume32
Issue number8
DOIs
StatePublished - Apr 28 2020

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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