Improved Figure of Merit of Cu 2 SnSe 3 via Band Structure Modification and Energy-Dependent Carrier Scattering

作者：Hongwei Ming, Chen Zhu, Xiaoying Qin, Jian Zhang, Di Li, Baoli Zhang, Tao Chen, Jimin Li, Xunuo Lou, Hongxin Xin · 发表于：ACS Applied Materials & Interfaces · 年份：2020 · DOI：10.1021/acsami.0c04298 · 被引用次数：36 · 研究领域：Advanced Thermoelectric Materials and Devices、Chalcogenide Semiconductor Thin Films、2D Materials and Applications

As an ecofriendly thermoelectric material with intrinsic low thermal conductivity, ternary diamond-like Cu 2 SnSe 3 (CSS) has attracted much attention. Nevertheless, its figure of merit, ZT, is limited by its small thermopower ( S ) and power factor (PF). Here, we show that an increase in thermopower by 63% and a carrier-mobility rise of 81% at 300 K can be simultaneously achieved through 5% substitution of Fe for Sn due to both enhancement of electronic density of states and degeneracy of multiple valence band maxima, which lead to high PF = 10.3 μW·cm –1 ·K –2 at 823 K for Fe-doped CSS (CSFS). Besides, an ultrahigh PF of 14.8 μW·cm –1 ·K –2 (at 773 K) and 45% reduction of lattice thermal conductivity (at 823 K) are realized for CSFS-based composites with 0.125 wt % of MgO nanoinclusions, owing to further enhancement of S via energy-dependent scattering and strong phonon scattering by the embedded nanoparticles. Consequently, a maximum ZT = 1 at 823 K is reached for the CSFS/ f MgO composite samples with f = 0.125 wt %, which is around 2.5 times larger than that of the CSS compound.