State Key Laboratory of Advanced Technology for Materials Synthesis and Processing , Wuhan University of Technology , Wuhan 430070 , China.
ACS Appl Mater Interfaces. 2018 Jul 5;10(26):22389-22400. doi: 10.1021/acsami.8b05080. Epub 2018 Jun 25.
Pristine CrSe is a narrow-band gap semiconductor but with an inferior ZT value of 0.22 obtained at 623 K. In this paper, we improve the thermoelectric performance of the CrSe material by optimizing carrier concentration, suppressing the bipolar thermal conductivity, and reducing the lattice thermal conductivity simultaneously. First, the effect of different dopants (Nb, Ni, and Mn) on the phase composition and thermoelectric transport properties of MCrSe (M = Nb, Ni, and Mn; x = 0-0.02) compounds are systematically investigated. The roles of those dopants are distinct. Mn-doped samples show superior thermoelectric properties in comparison with those of other-element-doped samples. Doping with Mn significantly increases the carrier concentration, accompanied with a suppression of the intrinsic excitation and a reduction of both the bipolar thermal conductivity and the lattice thermal conductivity of CrSe. To further reduce the thermal conductivity, we have synthesized Mn and S codoped MnCrSeS ( x = 0-0.1) samples. Alloying with S significantly decreases the lattice thermal conductivity and enlarges the band gap, boosting the Seebeck coefficient. The maximum ZT value of MnCrSeS reaches 0.33 at 823 K. Compared with the pristine CrSe sample, the maximum ZT value is increased by 50% and the temperature corresponding to the peak value shifts toward higher temperatures by 200 K.
原始 CrSe 是一种窄带隙半导体，但在 623 K 时获得的 ZT 值仅为 0.22。在本文中，我们通过优化载流子浓度、抑制双极热导率和同时降低晶格热导率来提高 CrSe 材料的热电性能。首先，系统研究了不同掺杂剂（Nb、Ni 和 Mn）对 MCrSe（M = Nb、Ni 和 Mn；x = 0-0.02）化合物的相组成和热电输运性能的影响。这些掺杂剂的作用是不同的。与其他元素掺杂的样品相比，Mn 掺杂的样品表现出优异的热电性能。Mn 掺杂显著增加了载流子浓度，同时抑制了本征激发，并降低了 CrSe 的双极热导率和晶格热导率。为了进一步降低热导率，我们合成了 Mn 和 S 共掺杂的 MnCrSeS（x = 0-0.1）样品。S 的合金化显著降低了晶格热导率并扩大了带隙，从而提高了 Seebeck 系数。MnCrSeS 的最大 ZT 值在 823 K 时达到 0.33。与原始 CrSe 样品相比，最大 ZT 值提高了 50%，峰值对应的温度向高温移动了 200 K。
