Achieving High Thermoelectric Figure of Merit in Polycrystalline SnSe via Introducing Sn Vacancies
Achieving High Thermoelectric Figure of Merit in Polycrystalline SnSe via Introducing Sn Vacancies
复制标题
通过引入 Sn 空位在多晶 SnSe 中实现高热电品质因数
DOI：
10.1021/jacs.7b11875
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发表时间：
2018-01-10
影响因子：
15
通讯作者：
Tang, Guodong
中科院分区：
文献类型：
--
作者：
Wei, Wei;Chang, Cheng;Tang, Guodong
热电发电技术已经成为一种清洁的“热机”，可以将热量转化为电能。最近，在SnSe晶体中发现的热电优值引起了极大的关注。鉴于其易于加工和放大应用，非常需要ZT值与SnSe晶体的ZT值相当的多晶SnSe材料。在这里，我们实现了创纪录的高ZT值类似于2.1在873 K的多晶Sn 1-xSe与Sn空位。我们表明，载流子浓度的增加，通过人为引入锡空位，有助于显着的电导率和热电功率因数的增强。根据第一性原理计算结果对数据进行了详细的分析，结果表明载流子浓度的增加可以归因于Sn空位引起的费米能级下移以及空位态和价带之间的相互作用。此外，空位打破平移对称性，从而增强声子散射，导致超低热导率。这种类似于2.1的高ZT值是通过协同优化多晶SnSe的电传输和热传输特性来实现的。多晶SnSe的ZT的大幅增加可能会加速这种材料在高效固态热电器件中的实际应用。
Thermoelectric power generation technology has emerged as a clean "heat engine" that can convert heat to electricity. Recently, the discovery of an ultrahigh thermoelectric figure of merit in SnSe crystals has drawn a great deal of attention. In view of their facile processing and scale-up applications, polycrystalline SnSe materials with ZT values comparable to those of the SnSe crystals are greatly desired. Here we achieve a record high ZT value similar to 2.1 at 873 K in polycrystalline Sn1-xSe with Sn vacancies. We demonstrate that the carrier concentration increases by artificially introducing Sn vacancies, contributing significantly to the enhancements of electrical conductivity and thermoelectric power factor. The detailed analysis of the data in the light of first-principles calculations results indicates that the increased carrier concentration can be attributed to the Sn-vacancy-induced Fermi level downshift and the interplay between the vacancy states and valence bands. Furthermore, vacancies break translation symmetry and thus enhance phonon scattering, leading to extralow thermal conductivity. Such high ZT value similar to 2.1 is achieved by synergistically optimizing both electrical- and thermal-transport properties of polycrystalline SnSe. The vast increase in ZT for polycrystalline SnSe may accelerate practical applications of this material in highly effective solid-state thermoelectric devices.