New two-dimensional phase of tin chalcogenides: Candidates for high-performance thermoelectric materials
Journal
Physical Review Materials
Journal Volume
3
Journal Issue
1
Start Page
013405
ISSN
24759953
Date Issued
2019
Author(s)
Abstract
Tin-chalcogenides SnX (X=Te, Se, and S) have been attracting research interest due to their thermoelectric physical properties. Their two-dimensional (2D) counterparts, which are expected to enhance those properties, nevertheless have not been fully explored because of many possible structures. A variable-composition exploration of 2D Sn1-xXx systems (X=Te, Se, and S) has been performed using a global searching method based on an evolutionary algorithm combined with density-functional calculations. A new hexagonal phase denoted by β′-SnX is found using Universal Structure Predictor: Evolutionary Xtallography (USPEX), and the structural stability has been further checked by calculations of phonons and elasticity. β′-SnTe is the most stable among all possible 2D phases of SnTe, including experimentally available phases. Further, β′ phases of SnSe and SnS are also found to be energetically close to the most stable phases. A high thermoelectronic (TE) performance has been predicted in the β′-SnX phases, which have a dimensionless figure of merit as high as ?0.96 to 3.81 for SnTe, ?0.93 to 2.51 for SnSe, and ?1.19 to 3.18 for SnS at temperatures ranging from 300 to 900 K with a practically attainable carrier concentration of 5×1012cm-2. The high TE performance results from a high power factor that is attributed to the quantum confinement of 2D materials and the band convergence near the Fermi level, as well as low thermal conductivity mainly from both low elastic constants due to weak inter-Sn bonding strength and strong lattice anharmonicity.
Subjects
Carrier Concentration
Chalcogenides
Iv-vi Semiconductors
Lattice Constants
Layered Semiconductors
Selenium Compounds
Stability
Thermal Conductivity
Thermoelectricity
Tin
Dimensionless Figure Of Merit
Lattice Anharmonicity
Low Thermal Conductivity
Research Interests
Structural Stabilities
Thermo-electric Materials
Two Dimensional (2 D)
Universal Structures
Tin Compounds
Publisher
American Physical Society revtex@aps.org
Type
journal article