title: Control of PbSe quantum dot surface chemistry and photophysics using an alkylselenide ligand.
abstract: We have synthesized alkylselenide reagents to replace the native oleate ligand on PbSe quantum dots (QDs) in order to investigate the effect of surface modification on their stoichiometry, photophysics, and air stability. The alkylselenide reagent removes all of the oleate on the QD surface and results in Se addition; however, complete Se enrichment does not occur, achieving a 53% decrease in the amount of excess Pb for 2 nm diameter QDs and a 23% decrease for 10 nm QDs. Our analysis suggests that the Se ligand preferentially binds to the {111} faces, which are more prevalent in smaller QDs. We find that attachment of the alkylselenide ligand to the QD surface enhances oxidative resistance, likely resulting from a more stable bond between surface Pb atoms and the alkylselenide ligand compared to Pb-oleate. However, binding of the alkylselenide ligand produces a separate nonradiative relaxation route that partially quenches PL, suggesting the formation of a dark hole-trap.
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Hughes
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Ruddy
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Blackburn
authors.forename: Danielle K
authors.initials: DK
authors.lastname: Smith
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Bergren
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Nozik
authors.forename: Justin C
authors.initials: JC
authors.lastname: Johnson
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Beard
mesh_terms: D003460:Crystallization / Q000379:methods; D007854:Lead / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D008422:Materials Testing; D045663:Quantum Dots; D012643:Selenium / Q000737:chemistry*; D018036:Selenium Compounds / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D018036:Selenium Compounds; C088065:lead selenide; D007854:Lead; D012643:Selenium