Theoretical and experimental investigations of the thermoelectric properties of Bi2S3
Theoretical and experimental investigations of the thermoelectric properties of Bi2S3
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DOI：
10.1063/1.4916528
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发表时间：
2015-03-28
影响因子：
3.2
通讯作者：
Dennler, Gilles
中科院分区：
文献类型：
--
作者：
Chmielowski, Radoslaw;Pere, Daniel;Dennler, Gilles
采用密度泛函理论和实验方法研究了不同掺杂量的Bi 2S 3的电子和输运性质。首先，热电性能的原理计算被用来评估的正交Bi 2S 3结构的热电势。非本征缺陷的计算筛选用于选择最有利的n型掺杂剂。在所考虑的所有掺杂剂中，铪和氯被确定为预期的掺杂剂，而例如，发现锗是不利的。这一点得到了实验的证实。在室温下对通过放电等离子体烧结获得的粒料进行塞贝克系数（S）和电导率（σ）测量。对于不同掺杂的化合物，观察到功率因数（S-2 σ）从大约50 μ W K-2 m（-1）增加到500 μ W K-2 m（-1）。在几个系列的样品中，我们观察到在室温下，当氯当量为0.25mol.%时，功率因数大于500 μ W K-2 m（-1）的最佳值BiCl 3。将所得结果绘制在半对数对数（sigma）与S图上，以证明存在将功率因数限制在500 μ W K-2 m（-1）左右的非常强的线性趋势。Bi 2S 3作为热电材料的进一步改进将需要找到新的掺杂模式，这将突破所观察到的趋势。稳定性测试结果表明，最佳掺杂的Bi_2S_3性质稳定。(C)2015 AIP Publishing LLC.
Electronic and transport properties of Bi2S3 with various dopants are studied using density functional theory and experimental characterizations. First, principle calculations of thermoelectric properties are used to evaluate the thermoelectric potential of the orthorhombic Bi2S3 structure. The computational screening of extrinsic defects is used to select the most favorable n-type dopants. Among all the dopants considered, hafnium and chlorine are identified as prospective dopants, whereas, e.g., germanium is found to be unfavorable. This is confirmed by experiment. Seebeck coefficient (S) and electrical conductivity (sigma) measurements are performed at room temperature on pellets obtained by spark plasma sintering. An increase of power factors (S-2.sigma) from around 50 up to 500 mu W K-2 m(-1) is observed for differently doped compounds. In several series of samples, we observed an optimum of power factor above 500 mu W K-2 m(-1) at room temperature for a chlorine equivalence of 0.25 mol.% BiCl3. The obtained results are plotted on a semilogarithmic log (sigma) versus S graph to demonstrate that a very strong linear trend that limits the power factor around 500 mu W K-2 m(-1) exists. Further improvement of Bi2S3 as thermoelectric material will require finding new doping modes that will break through the observed trend. The results of stability tests demonstrate that properties of optimally doped Bi2S3 are stable. (C) 2015 AIP Publishing LLC.