Enhanced thermoelectric properties of nanostructured n-type Bi2Te3 by suppressing Te vacancy through non-equilibrium fast reaction

By Yuan Wang, Weidi Liu, Xiaolei Shi, M. Hong, Lijun Wang, Meng Li, Hao Wang, Jin Zou, Zhigang Chen. Chemical Engineering Journal, 2020

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As one promising low-temperature thermoelectric material, Bi2Te3 suffers from high carrier concentrations beyond the optimal value contributed by excess Te vacancies. In this study, Te vacancies can be effectively suppressed in the n-type nanostructured Bi2Te3 via a non-equilibrium reaction induced by spark plasma sintering. The electron concentration has been greatly reduced from pristinely ~1 × 1020 to ~7 × 1019 cm−3, generating a decent power factor of 12.84 µW cm−1 K−2 at 320 K. Meanwhile, the decreased electronic thermal conductivity due to deteriorated electrical conductivity enables a very low thermal conductivity of 0.48 W m−1 K−1, which ultimately secures a promising peak figure of merit zT of ~1.1 at 420 K and an outstanding average zT of ~1 from 320 to 470 K. Such a high performance is one of the cutting-edge values reported in binary n-type Bi2Te3 so far. Our study provides a new insight into manipulating intrinsic point defects in nanostructured Bi2Te3 thermoelectric materials for achieving higher zT.

Subfields: Materials Chemistry, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/24ae90e998f21b04d5ce2b00a5d93a8329a30a45