title: Highly luminescent lead sulfide nanocrystals in organic solvents and water through ligand exchange with poly(acrylic acid).
abstract: Hydrophobic lead sulfide quantum dots (PbS/OA) synthesized in the presence of oleic acid were transferred from nonpolar organic solvents to polar solvents such as alcohols and water by a simple ligand exchange with poly(acrylic acid) (PAA). Ligand exchange took place rapidly at room temperature When a colloidal solution of PbS/OA in tetrahydrofuran (THF) was treated with excess PAA, the PbS/PAA nanocrystals that formed were insoluble in hexane and toluene but could be dissolved in methanol or water, where they formed colloidal solutions that were stable for months. Ligand exchange was accompanied by a small blue shift in the band-edge absorption, consistent with a small reduction in particle size. While there was a decrease in quantum yield associated with ligand exchange and transfer to polar solvents, as is commonly found for colloidal quantum dots, the quantum yields determined were impressively high: PbS/OA in toluene (82%) and in THF (58%); PbS/PAA in THF (42%) and in water (24%). The quantum yields for the PbS/PAA solutions decreased over time as the solutions were allowed to age in the presence of air.
authors.affiliation: Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Canada M5S 3H6.
authors.forename: Wanjuan
authors.initials: W
authors.lastname: Lin
authors.forename: Karolina
authors.initials: K
authors.lastname: Fritz
authors.forename: Gerald
authors.initials: G
authors.lastname: Guerin
authors.forename: Ghasem R
authors.initials: GR
authors.lastname: Bardajee
authors.forename: Sean
authors.initials: S
authors.lastname: Hinds
authors.forename: Vlad
authors.initials: V
authors.lastname: Sukhovatkin
authors.forename: Edward H
authors.initials: EH
authors.lastname: Sargent
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Scholes
authors.forename: Mitchell A
authors.initials: MA
authors.lastname: Winnik
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D009930:Organic Chemicals / Q000737:chemistry*; D045663:Quantum Dots; D012997:Solvents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013440:Sulfides / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D000180:Acrylic Resins; D008024:Ligands; D009930:Organic Chemicals; D012997:Solvents; D013440:Sulfides; D014867:Water; C018391:lead sulfide; D007854:Lead; C006903:carbopol 940