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Synergistical Enhancement of Thermoelectric Properties in n‐Type Bi 2 O 2 Se by Carrier Engineering and Hierarchical Microstructure
Author(s) -
Tan Xing,
Liu Yaochun,
Liu Rui,
Zhou Zhifang,
Liu Chan,
Lan JinLe,
Zhang Qinghua,
Lin YuanHua,
Nan CeWen
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201900354
Subject(s) - materials science , microstructure , dopant , thermal conductivity , thermoelectric effect , phonon scattering , thermoelectric materials , electrical resistivity and conductivity , electron mobility , doping , seebeck coefficient , analytical chemistry (journal) , nanodot , oxygen , nanotechnology , chemical engineering , optoelectronics , composite material , thermodynamics , electrical engineering , chemistry , organic chemistry , engineering , physics , chromatography
Oxygen‐containing compounds are promising thermoelectric (TE) materials for their chemical and thermal stability. As compared with the high‐performance p‐type counterparts (e.g., ZT ≈1.5 for BiCuSeO), the enhancement of the TE performance of n‐type oxygen‐containing materials remains challenging due to their mediocre electrical conductivity and high thermal conductivity. Here, n‐type layered Bi 2 O 2 Se is reported as a potential TE material, of which the thermal conductivity and electrical transport properties can be effectively tuned via carrier engineering and hierarchical microstructure. By selective modification of insulating [Bi 2 O 2 ] 2+ layers with Ta dopant, carrier concentration can be increased by four orders of magnitude (from 10 15 to 10 19 cm −3 ) while relatively high carrier mobility can be maintained, thus greatly enhancing the power factors (≈451.5 µW K −2 m −1 ). Meanwhile, the hierarchical microstructure can be induced by Ta doping, and the phonon scattering can be strengthened by atomic point defects, nanodots of 5–10 nm and grains of sub‐micrometer level, which progressively suppresses the lattice thermal conductivity. Accordingly, the ZT value of Bi 1.90 Ta 0.10 O 2 Se reaches 0.36 at 773 K, a ≈350% improvement in comparison with that of the pristine Bi 2 O 2 Se. The average ZT value of 0.30 from 500 to 823 K is outstanding among n‐type oxygen‐containing TE materials. This work provides a desirable way for enhancing the ZT values in oxygen‐containing compounds.