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Title: Using heterostructural alloying to tune the structure and properties of the thermoelectric Sn 1–xCa xSe

We grow and kinetically stabilize the isotropic rocksalt phase of SnSe thin films by alloying SnSe with CaSe. Thin polycrystalline films of the metastable heterostructural alloy Sn 1–xCa xSe are synthesized by pulsed laser deposition on amorphous SiO 2 over the entire composition range 0 < x < 1. We observe the theoretically-predicted, composition-driven change from a layered, orthorhombic structure to an isotropic, cubic structure near x = 0.18, in reasonable agreement with the theoretical value of x = 0.13 calculated from first principles. The optical band gap is highly non-linear in x and the trend agrees with theory predictions. Compared to the layered end-member SnSe, the isotropic alloy near the orthorhombic-to-rocksalt transition has a p-type electrical resistivity three orders of magnitude lower, and a thermoelectric power factor at least ten times larger. Furthermore manipulation of the structure of a functional material like SnSe via alloying may provide a new path to enhanced functionality, in this case, improved thermoelectric performance.
Authors:
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [4] ;  [1] ;  [1] ;  [4] ; ORCiD logo [3] ;  [4] ;  [5] ; ORCiD logo [4] ;  [4] ; ORCiD logo [1]
  1. Oregon State Univ., Corvallis, OR (United States)
  2. Univ. of Colorado, Boulder, CO (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  4. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  5. Colorado School of Mines, Golden, CO (United States)
Publication Date:
Report Number(s):
NREL/JA-5K00-70057
Journal ID: ISSN 2050-7488; JMCAET
Grant/Contract Number:
AC36-08GO28308; AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Journal of Materials Chemistry. A
Additional Journal Information:
Journal Volume: 5; Journal Issue: 32; Journal ID: ISSN 2050-7488
Publisher:
Royal Society of Chemistry
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Next Generation of Materials by Design: Incorporating Metastability (CNGMD); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; thin films; polycrystalline; thermoelectric performance
OSTI Identifier:
1379467
Alternate Identifier(s):
OSTI ID: 1390296