Layered Germanium-Selenium Compounds as Phonon-Glass Electron-Crystals: A Pathway to Enhance the Thermoelectric Performance.
basic_science · Level V
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- Record sourced from PubMed, PMID 40275463.
- Also identified by DOI 10.1021/acs.nanolett.4c06620.
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Abstract
The early concept of a "phonon-glass electron-crystal" for enhancing the thermoelectric figure of merit (<i>ZT</i>) is explored theoretically in layered Ge-Se crystals, where phonon transport exhibits glass-like behavior. <i>Ab initio</i> lattice dynamics and the rigid electronic band method project an ultrahigh <i>ZT</i> = 4.04 at 1000 K along the <i>a</i> axis in the high-temperature GeSe<sub>2</sub> phase at an electron doping concentration of 10<sup>20</sup> cm<sup>-3</sup>. Meanwhile, the low-temperature Ge<sub>4</sub>Se<sub>9</sub> phase achieves a high <i>ZT</i> = 2.19 at 600 K along the <i>a</i> axis with an electron doping concentration of 6 × 10<sup>19</sup> cm<sup>-3</sup>. These maximal values reflect the ultralow lattice thermal conductivity, 0.168 W m<sup>-1</sup> K<sup>-1</sup> (GeSe<sub>2</sub>, 1000 K) and 0.289 W m<sup>-1</sup> K<sup>-1</sup> (Ge<sub>4</sub>Se<sub>9</sub>, 600 K), and high power factor at optimized carrier concentrations along the <i>a</i> axis. Our calculations indicate a promising pathway for approaching the early concept of maximizing <i>ZT</i>, by tailoring carrier doping in layered crystals with glass-like phononic transport.