Schuler Raphael, Bianchini Federico, Norby Truls, Fjellvåg Helmer
Department of Chemistry, Centre for Materials Science and Nanotechnology (SMN), University of Oslo, P.O.B 1126 Blindern, 0318 Oslo, Norway.
ACS Appl Mater Interfaces. 2021 Feb 17;13(6):7416-7422. doi: 10.1021/acsami.0c19341. Epub 2021 Feb 5.
We report a near-broken-gap alignment between p-type FeWO and n-type FeWO, a model pair for the realization of Ohmic direct junction thermoelectrics. Both undoped materials have a large Seebeck coefficient and high electrical conductivity at elevated temperatures, due to inherent electronic defects. A band-alignment diagram is proposed based on X-ray photoelectron and ultraviolet-visible light reflectance spectroscopy. Experimentally acquired nonrectifying - characteristics and the constructed band-alignment diagram support the proposed formation of a near-broken-gap junction. We have additionally performed computational modeling based on density functional theory (DFT) on bulk models of the individual compounds to rationalize the experimental band-alignment diagram and to provide deeper insight into the relevant band characteristics. The DFT calculations confirm an Fe-3d character of the involved band edges, which we suggest is a decisive feature for the unusual band overlap.
我们报道了p型FeWO与n型FeWO之间近乎破裂能隙的对准，这是一对用于实现欧姆直接结热电材料的模型对。由于固有电子缺陷，两种未掺杂材料在高温下都具有较大的塞贝克系数和高电导率。基于X射线光电子能谱和紫外-可见反射光谱提出了能带对准图。实验获得的非整流特性和构建的能带对准图支持了所提出的近乎破裂能隙结的形成。我们还基于密度泛函理论（DFT）对单个化合物的体模型进行了计算建模，以合理化实验能带对准图，并更深入地了解相关能带特性。DFT计算证实了所涉及能带边缘的Fe-3d特性，我们认为这是异常能带重叠的决定性特征。
