Highly charged interface trap states in PbS1−x govern electro-thermal transport
Huan, Tran Doan
Montaño, Raul David
Pettes, Michael Thompson
AffiliationUniv Arizona, Dept Aerosp & Mech Engn
MetadataShow full item record
PublisherAMER INST PHYSICS
CitationYazdani, Sajad & Doan Huan, Tran & Liu, Yufei & Kashfi Sadabad, Raana & David Montaño, Raul & He, Jian & Thompson Pettes, Michael. (2019). Highly charged interface trap states in PbS 1− x govern electro-thermal transport. APL Materials. 7. 071105. 10.1063/1.5096786.
RightsCopyright © 2019 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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AbstractThis work describes our discovery of the dominant role of highly charged interfaces on the electrothermal transport properties of PbS, along with a method to reduce the barrier potential for charge carriers by an order of magnitude. High temperature thermoelectrics such as PbS are inevitably exposed to elevated temperatures during postsynthesis treatment as well as operation. However, we observed that as the material was heated, large concentrations of sulfur vacancy (VS..) sites were formed at temperatures as low as 266 degrees C. This loss of sulfur doped the PbS n-type and increased the carrier concentration, where these excess electrons were trapped and immobilized at interfacial defect sites in polycrystalline PbS with an abundance of grain boundaries. Sulfur deficient PbS0.81 exhibited a large barrier potential for charge carriers of 0.352 eV, whereas annealing the material under a sulfur-rich environment prevented VS.. formation and lowered the barrier by an order of magnitude to 0.046 eV. Through ab initio calculations, the formation of VS.. was found to be more favorable on the surface compared to the bulk of the material with a 1.72 times lower formation energy barrier. These observations underline the importance of controlling interface-vacancy effects in the preparation of bulk materials comprised of nanoscale constituents.
NoteOpen access journal
VersionFinal published version
SponsorsU. S. National Science Foundation [CAREER-1553987, REU-1560098]; UConn Research Foundation [PD17-0137]; U.S. Department of Energy Office of Science [89233218CNA000001]; GE Graduate Fellowship for Innovation; XSEDE through the computational resource allocation [TG-DMR170031]