title: High thermoelectric performance via hierarchical compositionally alloyed nanostructures.
abstract: Previous efforts to enhance thermoelectric performance have primarily focused on reduction in lattice thermal conductivity caused by broad-based phonon scattering across multiple length scales. Herein, we demonstrate a design strategy which provides for simultaneous improvement of electrical and thermal properties of p-type PbSe and leads to ZT ~ 1.6 at 923 K, the highest ever reported for a tellurium-free chalcogenide. Our strategy goes beyond the recent ideas of reducing thermal conductivity by adding two key new theory-guided concepts in engineering, both electronic structure and band alignment across nanostructure-matrix interface. Utilizing density functional theory for calculations of valence band energy levels of nanoscale precipitates of CdS, CdSe, ZnS, and ZnSe, we infer favorable valence band alignments between PbSe and compositionally alloyed nanostructures of CdS1-xSex/ZnS1-xSex. Then by alloying Cd on the cation sublattice of PbSe, we tailor the electronic structure of its two valence bands (light hole L and heavy hole Σ) to move closer in energy, thereby enabling the enhancement of the Seebeck coefficients and the power factor.
authors: Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
authors: Li-Dong
authors: LD
authors: Zhao
authors: Shiqiang
authors: S
authors: Hao
authors: Shih-Han
authors: SH
authors: Lo
authors: Chun-I
authors: CI
authors: Wu
authors: Xiaoyuan
authors: X
authors: Zhou
authors: Yeseul
authors: Y
authors: Lee
authors: Hao
authors: H
authors: Li
authors: Kanishka
authors: K
authors: Biswas
authors: Timothy P
authors: TP
authors: Hogan
authors: Ctirad
authors: C
authors: Uher
authors: C
authors: C
authors: Wolverton
authors: Vinayak P
authors: VP
authors: Dravid
authors: Mercouri G
authors: MG
authors: Kanatzidis