Enhanced thermoelectric performance in polymorphic heavily Co-doped Cu2SnS3 through carrier compensation by Sb substitution
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2021-05-02 |
| Journal | Science and Technology of Advanced Materials |
| Authors | Yaqing Zhao, Yan Gu, Peng Zhang, Xiaohui Hu, Yifeng Wang |
| Institutions | Tsinghua University, Nagoya Industrial Science Research Institute |
| Citations | 17 |
Abstract
Section titled āAbstractāHeavily acceptor-doped Cu<sub>2</sub>SnS<sub>3</sub> (CTS) shows promisingly large power factor (<i>PF</i>) due to its rather high electrical conductivity (<i>Ļ</i>) which causes a modest <i>ZT</i> with a high electronic thermal conductivity (<i>Īŗ<sub>e</sub></i> ). In the present work, a strategy of carrier compensation through Sb-doping at the Sn site in Cu<sub>2</sub>Sn<sub>0.8</sub>Co<sub>0.2</sub>S<sub>3</sub> was investigated, aiming at tailoring electrical and phonon transport properties simultaneously. Rietveld analysis suggested a complex polymorphic microstructure in which the cation-(semi)ordered tetragonal phase becomes dominant over the coherently bonded cation-disordered cubic phase, as is preliminarily revealed using TEM observation, upon Sb-doping and Sb would substitute Sn preferentially in the tetragonal structure. With increasing content of Sb, the <i>Ļ</i> was lowered and the Seebeck coefficient (<i>S</i>) was enhanced effectively, which gave rise to high <i>PF</i>s maintained at ~10.4 Ī¼Wcm<sup>-1</sup>K<sup>-2</sup> at 773 K together with an optimal reduction in <i>Īŗ<sub>e</sub></i> by 60-70% in the whole temperature range. The lattice thermal conductivity was effectively suppressed from 1.75 Wm<sup>-1</sup>K<sup>-1</sup> to ~1.2 Wm<sup>-1</sup>K<sup>-1</sup> at 323 K while maintained very low at 0.3-0.4 Wm<sup>-1</sup>K<sup>-1</sup> at 773 K. As a result, a peak <i>ZT</i> of ~0.88 at 773 K has been achieved for Cu<sub>2</sub>Sn<sub>0.74</sub>Sb<sub>0.06</sub>Co<sub>0.2</sub>S<sub>3</sub>, which stands among the tops so far of the CTS-based diamond-like ternary sulfides. These findings demonstrate that polymorphic microstructures with cation-disordered interfaces as an approach to achieve effective phonon-blocking and low lattice thermal conductivity, of which further crystal chemistry, microstructural and electrical tailoring are possible by appropriate doping.