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Germanium-Tin/Cadmium Sulfide Core/Shell Nanocrystals with Enhanced Near-Infrared Photoluminescence

TitleGermanium-Tin/Cadmium Sulfide Core/Shell Nanocrystals with Enhanced Near-Infrared Photoluminescence
Publication TypeJournal Article
Year of Publication2017
AuthorsBoote, BW, Men, L, Andaraarachchi, HP, Bhattacharjee, U, Petrich, JW, Vela, J, Smith, EA
JournalChemistry of Materials
Date Published07
Type of ArticleArticle
ISBN Number0897-4756
Accession NumberWOS:000406573200033
Keywordsalloy nanocrystals, chemistry, colloidal synthesis, energy-gap, ge nanocrystals, ge1-xsnx quantum dots, germanium, Materials Science, mesoporous, raman-spectroscopy, surface, tin, trichlorogermane-derived polymers

Ge1-xSnx alloy nanocrystals and Ge1-xSnx/CdS core/shell nanocrystals were prepared via solution phase synthesis, and their size, composition, and optical properties were characterized. The diameter of the nanocrystal samples ranged from 6 to 13 nm. The crystal structure of the Ge1-xSnx materials was consistent with a cubic diamond phase, while the CdS shell was consistent with the zinc blende polytype. Inclusion of Sn alone does not result in enhanced photoluminescence intensity; however, adding an epitaxial CdS shell onto the Ge1-xSnx nanocrystals does enhance the photoluminescence up to 15-fold versus that of Ge/CdS nanocrystals with a pure Ge core. More effective passivation of surface defects, and a consequent decrease in the level of surface oxidation, by the CdS shell as a result of improved epitaxy (smaller lattice mismatch) is the most likely explanation for the increased photoluminescence observed for the Ge1-xSnx/CdS materials. With enhanced photoluminescence in the near-infrared region, Ge1-xSnx core/shell nanocrystals might be useful alternatives to other materials for energy capture and conversion applications and as imaging probes.

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