Tin-Substituted Chalcopyrite: An n-Type Sulfide with Enhanced Thermoelectric Performance.
Tin-Substituted Chalcopyrite: An n-Type Sulfide with Enhanced Thermoelectric Performance.
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锡取代黄铜矿：一种热电性能增强的n型硫化物。
DOI：
10.1021/acs.chemmater.2c00637
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发表时间：
2022-07-12
影响因子：
8.6
通讯作者：
V. Powell, Anthony
中科院分区：
文献类型：
--
作者：
Tippireddy, Sahil;Azough, Feridoon;Vikram;Tompkins, Frances Towers;Bhui, Animesh;Freer, Robert;Grau-Crespo, Ricardo;Biswas, Kanishka;Vaqueiro, Paz;V. Powell, Anthony
热电性能与其p型类似物相当的n型硫化物的缺乏在全硫化物器件的制造中提出了一个问题。黄铜矿（CuFeS 2）提供了一个罕见的n型硫化物的例子。采用化学取代法制备Cu_（1-x）Sn_xFe_（S2）（0 ≤ x ≤ 0. 1），提高黄铜矿的热电性能。替代诱导高水平的质量和应变场的波动，导致晶格软化和增强的点缺陷散射。再加上位错和孪生确定的透射电子显微镜，这提供了一个机制，散射声子具有广泛的平均自由程。取代的材料保持大的态密度有效质量，因此，高塞贝克系数。结合高电荷载流子迁移率和高电导率，实现了功率因数的3倍提高。密度泛函理论（DFT）的计算表明，取代导致创建小的极化子，涉及本地化的Fe 2+状态，证实了X射线光电子能谱。小极化子的形成限制了载流子浓度的增加，使其值低于电子计数的预期值。一个改进的功率因数，再加上晶格热导率大幅减少（高达40%），增加了300%的最大品质因数，zT 0.3在673 K的Cu0.96Sn0.04FeS2。
The dearth of n-type sulfides with thermoelectric performance comparable to that of their p-type analogues presents a problem in the fabrication of all-sulfide devices. Chalcopyrite (CuFeS2) offers a rare example of an n-type sulfide. Chemical substitution has been used to enhance the thermoelectric performance of chalcopyrite through preparation of Cu1-xSnxFeS2 (0 ≤ x ≤ 0.1). Substitution induces a high level of mass and strain field fluctuation, leading to lattice softening and enhanced point-defect scattering. Together with dislocations and twinning identified by transmission electron microscopy, this provides a mechanism for scattering phonons with a wide range of mean free paths. Substituted materials retain a large density-of-states effective mass and, hence, a high Seebeck coefficient. Combined with a high charge-carrier mobility and, thus, high electrical conductivity, a 3-fold improvement in power factor is achieved. Density functional theory (DFT) calculations reveal that substitution leads to the creation of small polarons, involving localized Fe2+ states, as confirmed by X-ray photoelectron spectroscopy. Small polaron formation limits the increase in carrier concentration to values that are lower than expected on electron-counting grounds. An improved power factor, coupled with substantial reductions (up to 40%) in lattice thermal conductivity, increases the maximum figure-of-merit by 300%, to zT ≈ 0.3 at 673 K for Cu0.96Sn0.04FeS2.
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