Conductivity in Open-Framework Chalcogenides Tuned via Band Engineering and Redox Chemistry
Conductivity in Open-Framework Chalcogenides Tuned via Band Engineering and Redox Chemistry
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DOI：
10.1021/acs.chemmater.1c04285
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发表时间：
2022-02-22
影响因子：
8.6
通讯作者：
Brozek, Carl K.
中科院分区：
文献类型：
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作者：
McKenzie, Jacob;Le, Khoa N.;Brozek, Carl K.
“开放框架硫属化物”是一类重要的材料，它将孔隙率与半导体行为结合起来，但其导电性的基本方面仍未得到探索。在这里，我们报告了一种针对材料 TMA(2)MGe(4)Q(10) 标志性子类（TMA = 四甲基铵；M = Mn、Fe、Co、Ni、Zn；Q = S、Se）的组合实验计算方法。直流 (DC) 电导率测量和密度泛函理论 (DFT) 建模表明，金属离子和硫属化物特性主导着能带结构的关键特性，而阻抗谱则揭示了 Fe 框架中的纯电子能带型输运以及其他框架中的氧化还原型混合离子-电子电导率。氧化还原化学和计算表明，Fe 独特的电导率源于其倾向于使用 Fe-2(+)/Fe3+ 混合价作为 p 型掺杂源，以及其确保高载流子迁移率的高度共价键。总而言之，这些结果表明开放框架硫属化物是理解多孔半导体和实现高度可调电子性能的明确平台。
"Open-framework chalcogenides" are an important class of materials that combine porosity with semiconductor behavior, and yet fundamental aspects of their conductivity remain unexplored. Here, we report a combined experimental-computational approach to the iconic subclass of materials TMA(2)MGe(4)Q(10) (TMA = tetramethyl ammonium; M = Mn, Fe, Co, Ni, Zn; Q = S, Se). Direct current (DC) conductivity measurements and density functional theory (DFT) modeling reveal that metal ion and chalcogenide identities dominate key properties of the band structures, while impedance spectroscopy reveals purely electronic band-type transport in the Fe frameworks and redox-type mixed ion-electron conductivity in the others. Redox chemistry and computation suggest that the unique conductivity of Fe arises from its propensity toward Fe-2(+)/Fe3+ mixed valency as a source of p-type doping and from its highly covalent bonds that ensure high carrier mobilities. Taken together, these results demonstrate open-framework chalcogenides as a well-defined platform for understanding porous semiconductors and for achieving highly tunable electronic performance.