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 language | English (US) |
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Pages (from-to) | 3561-3569 |
Number of pages | 9 |
Journal | Chemistry of Materials |
Volume | 32 |
Issue number | 8 |
DOIs | |
State | Published - Apr 28 2020 |
Funding
This work was primarily supported by the Department of Energy, Office of Science, Basic Energy Sciences under grant DE-SC0014520. This work also made use of the EPIC facility of Northwestern University’s NU ANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; the State of Illinois through the IIN; and the Office of Science, U.S. Department of Energy under Contract Nos. DE-AC02-06CH11357 and DE-AC02-05CH11231. Access to facilities of high-performance computational resources at the Northwestern University is acknowledged.
ASJC Scopus subject areas
- General Chemistry
- General Chemical Engineering
- Materials Chemistry