Gate-Tunable Polar Optical Phonon to Piezoelectric Scattering in Few-Layer Bi<sub>2</sub> O<sub>2</sub> Se for High-Performance Thermoelectrics.
basic_science · Level V
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- Record sourced from PubMed, PMID 33314362.
- Also identified by DOI 10.1002/adma.202004786.
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Abstract
Atomically thin Bi<sub>2</sub> O<sub>2</sub> Se has emerged as a new member in 2D materials with ultrahigh carrier mobility and excellent air-stability, showing great potential for electronics and optoelectronics. In addition, its ferroelectric nature renders an ultralow thermal conductivity, making it a perfect candidate for thermoelectrics. In this work, the thermoelectric performance of 2D Bi<sub>2</sub> O<sub>2</sub> Se is investigated over a wide temperature range (20-300 K). A gate-tunable transition from polar optical phonon (POP) scattering to piezoelectric scattering is observed, which facilitates the capacity of drastic mobility engineering in 2D Bi<sub>2</sub> O<sub>2</sub> Se. Consequently, a high power factor of more than 400 µW m<sup>-1</sup> K<sup>-2</sup> over an unprecedented temperature range (80-200 K) is achieved, corresponding to the persistently high mobility arising from the highly gate-tunable scattering mechanism. This finding provides a new avenue for maximizing thermoelectric performance by changing the scattering mechanism and carrier mobility over a wide temperature range.