期刊
ACS APPLIED MATERIALS & INTERFACES
卷 12, 期 39, 页码 43901-43910出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.0c10236
关键词
high mobility; thermoelectric; 2D material; strain effect; Te
资金
- National Natural Science Foundation of China [11704258]
- Shenzhen Science, Technology and Innovation Commission [JCYJ20170412105922384]
- Natural Science Foundation of Guangdong Province [2017A030310377]
In line with the classic phonon-glass electron-crystal (PGEC) paradigm, semiconducting and semimetallic multinary compounds remain the cornerstone of the state-of-the-art thermoelectric materials. By contrast, elemental PGEC is very rare. In this work, we report a thermoelectric study of monolayer alpha-Te by first-principles calculations and solving the parameter-free Boltzmann transport equation. It is found that monolayer alpha-Te possesses high electron mobility (about 2500 cm(2) V-1 s(-)1) at room temperature due to small effective mass, low phonon frequencies, and thus a restricted phase space for electron-phonon scattering. In monolayer alpha-Te, the electrons near the conduction band edge are mainly scattered by the heavily populated quadratically dispersing out-of-plane acoustic (ZA) phonon modes. The thermoelectric figure of merit (ZT) for n-type monolayer alpha-Te is 0.55 at 300 K and 1.46 at 700 K. Notably, tensile strain stiffens the ZA modes, yielding a linear energy-momentum dispersion relation and the removal of the diverging thermal population of ZA phonons. Consequently, the electron mobility is enhanced. At a 4% tensile strain, the electron mobility can reach up to 8000 cm(2) V-1 s(-1) at room temperature while the thermal conductivity is almost unaffected, yielding a state-of-the-art ZT value of 0.94 and 2.03 in n-type monolayer alpha-Te at 300 and 700 K, respectively. For completeness, the thermoelectric study of p-type monolayer alpha-Te is also conducted. These results beckon further experiments toward high-performance alpha-Te-based thermoelectric materials via doping, alloying, and compositing.
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