期刊
ENERGY & ENVIRONMENTAL SCIENCE
卷 13, 期 1, 页码 200-211出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c9ee03087e
关键词
-
资金
- Department of Energy, Office of Science, Basic Energy Sciences [DE-SC0014520]
- Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource [NSF ECCS-1542205]
- MRSEC program at the Materials Research Center [NSF DMR-1720139]
- International Institute for Nanotechnology (IIN)
- Keck Foundation
- State of Illinois, through the IIN
- Office of Science of the U.S. Department of Energy [DE-AC02-06CH11357, DE-AC02-05CH11231]
- ONR [N00014-18-1-2102]
- National Science Foundation [DMR-1644779, DMR-1847038]
- State of Florida
- U.S. Department of Energy [DE-SC0018941]
- U.S. Department of Energy (DOE) [DE-SC0018941] Funding Source: U.S. Department of Energy (DOE)
We report a novel hierarchical microstructure in the PbSe-CdSe system, which collectively contributes to significant enhancement in thermoelectric performance, with ZT(ave) similar to 0.83 across the 400-923 K temperature range, the highest reported for p-type, Te-free PbSe systems. We have investigated the local atomic structure as well as the microstructure of a series of PbSe-xCdSe materials, up to x = 10%. We find that the behavior of the Cd atoms in the octahedral rock salt sites is discordant and results in off-center displacement and distortion. Such off-centered Cd in the PbSe matrix creates (1) L-sigma electronic energy band convergence, (2) a flattened L band, both contributing to higher Seebeck coefficients, and (3) enhanced phonon scattering, which leads to lower thermal conductivity. These conclusions are supported by photoemission yield spectroscopy in air (PYSA), solid state Cd-111, Se-77 NMR spectroscopy and DFT calculations. Above the solubility limit (>6%CdSe), we also observe endotaxial CdSe nano-precipitates with core-shell architecture formed in PbSe, whose size, distribution and structure gradually change with the Cd content. The nano-precipitates exhibit a zinc blende crystal structure and a tetrahedral shape with significant local strain, but are covered with a thin wurtzite layer along the precipitate/matrix interface, creating a core-shell structure embedded in PbSe. This newly discovered architecture causes a further reduction in lattice thermal conductivity. Moreover, potassium is found to be an effective p-type dopant in the PbSe-CdSe system, leading to an enhanced power factor, a maximum ZT of similar to 1.4 at 923 K for Pb0.98K0.02Se-6%CdSe.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据