Cu2Te Incorporation-Induced High Average Thermoelectric Performance in p-Type Bi2Te3 Alloys

Qing Shi; Xuanwei Zhao; Yiyuan Chen; Liwei Lin; Ding Ren; Bo Liu; Chunliang Zhou; Ran Ang

doi:10.1021/acsami.2c13527

Cu₂Te Incorporation-Induced High Average Thermoelectric Performance in p-Type Bi₂Te₃ Alloys

ACS Appl Mater Interfaces. 2022 Oct 12;14(40):45582-45589. doi: 10.1021/acsami.2c13527. Epub 2022 Sep 28.

Authors

Qing Shi¹, Xuanwei Zhao¹, Yiyuan Chen¹, Liwei Lin¹, Ding Ren¹, Bo Liu¹, Chunliang Zhou², Ran Ang^{1

3}

Affiliations

¹ Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China.
² Yantai Research Institute, Harbin Engineering University, Yantai 264006, China.
³ Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065, China.

PMID: 36170600
DOI: 10.1021/acsami.2c13527

Abstract

p-Type (Bi, Sb)₂Te₃ alloys are attractive materials for near-room-temperature thermoelectric applications due to their high atomic masses and large spin-orbit interactions. However, their narrow band gaps originating from spin-orbit interactions lead to bipolar excitation, thereby limiting average thermoelectrics within a local temperature region (300-400 K). Here, we introduce Cu₂Te into the Bi_0.3Sb_1.7Te₃ (BST) lattice to implement high thermoelectrics over a wide temperature range. The carrier concentration is synergistically modulated via Cu substitution and the evolution of intrinsic point defects (antisites and vacancies). Furthermore, the chain effect caused by Cu₂Te incorporation in BST is reflected in the improvement of the weighted mobility μ_W, thereby enhancing the power factor in the whole temperature range. Extrinsic and intrinsic defects due to the incorporation of Cu₂Te lead to a significant reduction in the lattice thermal conductivity κ_L, which is further demonstrated by Raman spectroscopy. Combining κ_L and μ_W, the quantity factor B increases from 0.5 to 1 with increasing Cu₂Te content due to not only the reduction of κ_L but also a significant improvement in electrical properties. Eventually, a peak figure of merit (zT) of ∼1.15 at 423 K is achieved in BST-Cu₂Te samples, and an average figure of merit (zT_ave) of ∼1.12 (350-500 K) surpasses other excellent p-type Bi₂Te₃-based thermoelectrics. Such a synergistic effect can facilitate near-room-temperature thermoelectric applications of Bi₂Te₃-based alloys and provide chances for the technology space in thermoelectrics.

Keywords: Sb)2Te3 alloys; average figure of merit; defect modulation; lattice thermal conductivity; p-type (Bi; thermoelectricity; weighted mobility.