Enhancement of electrical performance via carrier modulation in single crystalline PbTe prepared by Pb-flux method
Enhancement of electrical performance via carrier modulation in single crystalline PbTe prepared by Pb-flux method
复制标题
通过 Pb-flux 法制备的单晶 PbTe 的载流子调制增强电性能
DOI：
10.1016/j.jallcom.2018.09.363
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发表时间：
2019-02-05
影响因子：
6.2
通讯作者：
Deng, Shukang
中科院分区：
文献类型：
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作者：
Chen, Zhong;Tang, Yu;Deng, Shukang
采用铅助熔剂法，按照Pb 1 +xTe（x = 1.5，2.0，2.5和3.0）的化学计量比制备了PbTe单晶样品。实验结果表明，所有样品都具有n型导电性。载流子浓度的数量级为1019，比纯n型PbTe样品（2.56 × 1018 cm（-3））高一个数量级。x = 1.5的样品在420 K时的最高功率因数达到2.07 × 10（-3）W m（-1）K-2，与多晶样品（1.59 × 10（-3）W m（-1）K-2）相比提高了约30%。在对PbTe系统的理论研究中发现，在富Pb条件下，Te空位（V-Te）优先形成。为了进一步了解V-Te对PbTe热电材料电学性能的影响，采用第一性原理计算方法确定了V-Te掺杂PbTe的电子结构。理论计算表明，V-Te通过引入共振能级改变了电子态密度，从而增加了载流子袋的数目。因此，载流子浓度显著增加。本研究中采用铅助熔剂法合成PbTe单晶热电材料，方法简便，成本低，具有工业化生产的潜力。(C)2018爱思唯尔B. V.保留所有权利。
Single crystalline PbTe samples are prepared by the Pb-flux method according to the stoichiometric ratio of Pb1+xTe (x = 1.5, 2.0, 2.5, and 3.0). Experimental results show that all the samples exhibit n-type conductivity. The order of magnitude for carrier concentration is 1019, which is one order of magnitude higher than that in pure n-type PbTe sample (2.56 x 1018 cm(-3)). The highest power factor reaches 2.07 x 10(-3) W m(-1) K-2 at 420 K for the sample with x = 1.5, which is an approximately 30% enhancement compared with the polycrystalline sample (1.59 x 10(-3) W m(-1) K-2). In a theoretical study on the PbTe system, Te vacancy (V-Te) is preferentially formed under the Pb-rich condition. To further understand the effect of V-Te on the electrical performance of PbTe thermoelectric material, the electronic structures of PbTe with V-Te are determined by first principle calculations. Theoretical calculations reveal that V-Te can modify the electronic density of states by introducing resonant level, which can increase the number of carrier pockets. Consequently, carrier concentration has increased remarkably. In this study, a Pb-flux method for synthetizing single crystalline PbTe thermoelectric material is convenient and low cost, and it has potential for mass production in commercial applications. (C) 2018 Elsevier B.V. All rights reserved.