title: Infrared emitting and photoconducting colloidal silver chalcogenide nanocrystal quantum dots from a silylamide-promoted synthesis.
abstract: Here, we present a hot injection synthesis of colloidal Ag chalcogenide nanocrystals (Ag(2)Se, Ag(2)Te, and Ag(2)S) that resulted in exceptionally small nanocrystal sizes in the range between 2 and 4 nm. Ag chalcogenide nanocrystals exhibit band gap energies within the near-infrared spectral region, making these materials promising as environmentally benign alternatives to established infrared active nanocrystals containing toxic metals such as Hg, Cd, and Pb. We present Ag(2)Se nanocrystals in detail, giving size-tunable luminescence with quantum yields above 1.7%. The luminescence, with a decay time on the order of 130 ns, was shown to improve due to the growth of a monolayer thick ZnSe shell. Photoconductivity with a quantum efficiency of 27% was achieved by blending the Ag(2)Se nanocrystals with a soluble fullerene derivative. The co-injection of lithium silylamide was found to be crucial to the synthesis of Ag chalcogenide nanocrystals, which drastically increased their nucleation rate even at relatively low growth temperatures. Because the same observation was made for the nucleation of Cd chalcogenide nanocrystals, we conclude that the addition of lithium silylamide might generally promote wet-chemical synthesis of metal chalcogenide nanocrystals, including in as-yet unexplored materials.
authors.affiliation: Institute for Semiconductor and Solid State Physics, University Linz , Altenbergerstr. 69, Linz 4040, Austria. maksym.yarema@jku.at
authors.forename: Maksym
authors.initials: M
authors.lastname: Yarema
authors.forename: Stefan
authors.initials: S
authors.lastname: Pichler
authors.forename: Mykhailo
authors.initials: M
authors.lastname: Sytnyk
authors.forename: Robert
authors.initials: R
authors.lastname: Seyrkammer
authors.forename: Rainer T
authors.initials: RT
authors.lastname: Lechner
authors.forename: Gerhard
authors.initials: G
authors.lastname: Fritz-Popovski
authors.forename: Dorota
authors.initials: D
authors.lastname: Jarzab
authors.forename: Krisztina
authors.initials: K
authors.lastname: Szendrei
authors.forename: Roland
authors.initials: R
authors.lastname: Resel
authors.forename: Oleksandra
authors.initials: O
authors.lastname: Korovyanko
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Loi
authors.forename: Oskar
authors.initials: O
authors.lastname: Paris
authors.forename: Günter
authors.initials: G
authors.lastname: Hesser
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Heiss
mesh_terms: D000577:Amides / Q000737:chemistry* / Q000528:radiation effects; D018011:Chalcogens / Q000737:chemistry* / Q000528:radiation effects*; D003102:Colloids / Q000737:chemistry / Q000528:radiation effects; D003460:Crystallization / Q000379:methods; D007259:Infrared Rays; D008027:Light; D008029:Lighting / Q000379:methods*; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure; D045663:Quantum Dots; D012834:Silver / Q000737:chemistry* / Q000528:radiation effects; D013499:Surface Properties
chemical_list: D000577:Amides; D018011:Chalcogens; D003102:Colloids; D012834:Silver