Estimation of the Highest Thermoelectric Performance of the Bi-Doped SnTe at Room Temperature
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Published:2023-12-05
Issue:12
Volume:61
Page:915-922
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ISSN:1738-8228
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Container-title:Korean Journal of Metals and Materials
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language:en
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Short-container-title:Korean J. Met. Mater.
Author:
Lee Joonha,Park Hyunjin,Kim Jeong-Yeon,Seo Won-Seon,Yang Heesun,Aydemir Umut,Kim Se Yun,Shin Weon Ho,Kim Hyun-Sik
Abstract
SnTe has drawn much attention due to its Pb-free composition along with tunable electronic and lattice structures. However, its intrinsically high defect concentration and high lattice thermal conductivity (<i>κ<sub>1</sub></i>) have hindered its application in devices. Recently, Bi doping at Sn-sites in Sn<sub>1-<i>x</i></sub>Bi<sub><i>x</i></sub>Te (<i>x</i> = 0.0 – 0.08) has been demonstrated to be effective in improving the thermoelectric performance (<i>zT</i>) of SnTe. Bi doping was particularly effective in improving the Seebeck coefficient in a wide range of temperature while suppressing its <i>κ<sub>1</sub></i>. However, the effect of Bi doping on electronic band structure of SnTe has not been studied. Here, we applied the Single Parabolic Band (SPB) model to the room temperature electronic transport properties measurements (Seebeck coefficient, electrical conductivity, Hall carrier concentration) and analyzed how electronic band parameters like the density-of-states effective mass (<i>m<sub>d</sub></i> *), non-degenerate mobility (<i>μ<sub>0</sub></i>), weighted mobility (<i>μ<sub>w</sub></i>), and <i>B</i>-factor changes with a changing Bi doping content (<i>x</i>). As the <i>x</i> increases, the <i>m<sub>d</sub></i> * increases while <i>μ<sub>0</sub></i> decreases. As the <i>μ<sub>w</sub></i> depends both on <i>m<sub>d</sub></i> * and <i>μ<sub>0</sub></i>, it peaks at <i>x</i> = 0.02. Lastly, the <i>B</i>-factor is related to the ratio of <i>μ<sub>w</sub></i> to <i>κ<sub>1</sub></i>, due to significantly decreasing <i>κ<sub>1</sub></i> at high <i>x</i>, the <i>B</i>-factor also becomes the highest at <i>x</i> = 0.08. Based on the <i>B</i>-factor of <i>x</i> = 0.08 sample, the highest theoretical <i>zT</i> of 0.31 is predicted using the SPB model. This is approximately 2.2 times higher than the experimental <i>zT</i> (~0.139) reported in literature at 300 K. The SPB model also guides us that the highest theoretical <i>zT</i> of 0.31 can be achieved if its Hall carrier concentration is tuned to 9.06 × 10<sup>18</sup> cm<sup>-3</sup>.
Funder
University of Seoul
National Research Foundation of Korea
Ministry of Education
Ministry of Trade, Industry and Energy
Publisher
The Korean Institute of Metals and Materials
Subject
Metals and Alloys,Surfaces, Coatings and Films,Modeling and Simulation,Electronic, Optical and Magnetic Materials