In:
Journal of Materials Chemistry C, Royal Society of Chemistry (RSC), Vol. 10, No. 20 ( 2022), p. 7970-7979
Abstract:
In state-of-the-art bismuth telluride based thermoelectric devices, the n-type composition shows a lower figure-of-merit ( zT ) than the p-type counterpart due to intrinsic electrical anisotropy and bipolar conduction at elevated temperatures. Herein, we demonstrate a significant improvement in the zT values of n-type Bi 2− x Zn x Te 3 ( x = 0–0.3) materials through aliovalent Zn doping at the Bi-site in the rhombohedral Bi 2 Te 3 structure. A simultaneous enhancement in the electrical conductivity ( σ ) and Seebeck coefficient ( α ) with Zn doping is observed, which is attributed to the increased carrier concentration ( n ) and effective mass ( m *), respectively. Concomitantly, a drastic enhancement in the power factor ( α 2 σ ) from 2.4 mW m −1 K −2 ( x = 0) to 3.1 mW m −1 K −2 ( x = 0.2) at 430 K is achieved. In addition, the incorporation of Zn shows a significant reduction in the lattice and bipolar contributions to the total thermal conductivity ( κ ), which drastically enhances the zT value to ∼1.2 ( x = 0.2) at 450 K. The achieved zT value is ∼70% higher than that of the undoped Bi 2 Te 3 sample. A unicouple module fabricated using n-type Bi 1.8 Zn 0.2 Te 3 in combination with the compatible high zT p-type Bi 0.5 Sb 1.495 Cu 0.005 Te 3 material shows a record-high conversion efficiency ( η ) of ∼8.1% at a temperature gradient (Δ T ) of 224 K. The achieved η is amongst the best-reported values till date in Bi 2 Te 3 lab-scale thermoelectric power generators.
Type of Medium:
Online Resource
ISSN:
2050-7526
,
2050-7534
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
2702245-6
detail.hit.zdb_id:
2705156-0
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