Gate-Tunable Polar Optical Phonon to Piezoelectric Scattering in Few-Layer Bi2 O2 Se for High-Performance Thermoelectrics.
Atomically thin Bi2 O2 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 Bi2 O2 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 Bi2 O2 Se. Consequently, a high power factor of more than 400 µW m-1  K-2 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.
['Yang|Fang|F|', 'Wu|Jing|J|https://orcid.org/0000-0002-4182-6701', 'Suwardi|Ady|A|', 'Zhao|Yunshan|Y|', 'Liang|Boyuan|B|', 'Jiang|Jie|J|', 'Xu|Jianwei|J|', 'Chi|Dongzhi|D|', 'Hippalgaonkar|Kedar|K|', 'Lu|Junpeng|J|', 'Ni|Zhenhua|Z|']
polarization mobility scattering mechanisms Bi
2O
2Se piezoelectric materials thermoelectric materials