title: Two-Step Phase Transition in SnSe and the Origins of its High Power Factor from First Principles.
abstract: The interest in improving the thermoelectric response of bulk materials has received a boost after it has been recognized that layered materials, in particular SnSe, show a very large thermoelectric figure of merit. This result has received great attention while it is now possible to conceive other similar materials or experimental methods to improve this value. Before we can now think of engineering this material it is important we understand the basic mechanism that explains this unusual behavior, where very low thermal conductivity and a high thermopower result from a delicate balance between the crystal and electronic structure. In this Letter, we present a complete temperature evolution of the Seebeck coefficient as the material undergoes a soft crystal transformation and its consequences on other properties within SnSe by means of first-principles calculations. Our results are able to explain the full range of considered experimental temperatures.
authors.affiliation: CESAM, QMAT, European Theoretical Spectroscopy Facility, Université de Liège, allée du 6 août, 19, B-4000 Liège, Belgium.
authors.forename: Antoine
authors.initials: A
authors.lastname: Dewandre
authors.affiliation: Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA.|Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden.
authors.forename: Olle
authors.initials: O
authors.lastname: Hellman
authors.affiliation: ICAMS, Ruhr-Universität Bochum, 44780 Bochum, Germany.
authors.forename: Sandip
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: Department of Physics, West Virginia University, 207 White Hall, 26506 West Virginia, USA.|Facultad de Ingenieria, Benemerita Universidad Autonoma de Puebla, 72570 Puebla, Pue., Mexico.
authors.forename: Aldo H
authors.initials: AH
authors.lastname: Romero
authors.affiliation: Institute of Materials Chemistry, TU Wien, A-1060 Vienna, Austria.
authors.forename: Georg K H
authors.initials: GK
authors.lastname: Madsen
authors.affiliation: CESAM, QMAT, European Theoretical Spectroscopy Facility, Université de Liège, allée du 6 août, 19, B-4000 Liège, Belgium.
authors.forename: Matthieu J
authors.initials: MJ
authors.lastname: Verstraete