Achieving zT > 2 in p-Type AgSbTe2-xSex Alloys via Exploring the Extra Light Valence Band and Introducing Dense Stacking Faults
Achieving zT > 2 in p-Type AgSbTe2-xSex Alloys via Exploring the Extra Light Valence Band and Introducing Dense Stacking Faults
复制标题
DOI：
10.1002/aenm.201702333
复制
发表时间：
2018-03-26
影响因子：
27.8
通讯作者：
Zou, Jin
中科院分区：
文献类型：
--
作者：
Hong, Min;Chen, Zhi-Gang;Zou, Jin
p型AgSbTe2-xSex合金通过设计额外的光带来提高功率因数，并通过引入高密度的层错来增强声子散射，从而实现了超过2.0的优异值。密度泛函理论计算证实了AgSbTe2中存在具有较大简并度的光价带，并且与Se的合金化减小了光价带与最大价带之间的能量偏移。因此，p型AgSbTe2-xSex合金的功率因数显著提高。此外，透射电镜研究表明，层错和晶界的出现，与晶界和点缺陷一起显著增强了声子散射，导致超低导热系数。本研究提出的同时增强功率因数和增强声子散射的协同策略为定制热电性能开辟了一条稳健的途径。
Through simultaneously enhancing the power factor by engineering the extra light band and enhancing phonon scatterings by introducing a high density of stacking faults, a record figure-of-merit over 2.0 is achieved in p-type AgSbTe2-xSex alloys. Density functional theory calculations confirm the presence of the light valence band with large degeneracy in AgSbTe2, and that alloying with Se decreases the energy offset between the light valence band and the valence band maximum. Therefore, a significantly enhanced power factor is realized in p-type AgSbTe2-xSex alloys. In addition, transmission electron microscopy studies indicate the appearance of stacking faults and grain boundaries, which together with grain boundaries and point defects significantly strengthen phonon scatterings, leading to an ultralow thermal conductivity. The synergetic strategy of simultaneously enhancing power factor and strengthening phonon scattering developed in this study opens up a robust pathway to tailor thermoelectric performance.