Organic-to-aqueous phase transfer of cadmium chalcogenide quantum dots using a sulfur-free ligand for enhanced photoluminescence and oxidative stability

Raul Calzada, Christopher M. Thompson, Dana E. Westmoreland, Kedy Edme, Emily A Weiss

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

This paper describes a procedure for transferring colloidal CdS and CdSe quantum dots (QDs) from organic solvents to water by exchanging their native hydrophobic ligands for phosphonopropionic acid (PPA) ligands, which bind to the QD surface through the phosphonate group. This method, which uses dimethylformamide as an intermediate transfer solvent, was developed in order to produce high-quality water-soluble QDs with neither a sulfur-containing ligand nor a polymer encapsulation layer, both of which have disadvantages in applications of QDs to photocatalysis and biological imaging. CdS (CdSe) QDs were transferred to water with a 43% (48%) yield using PPA. The photoluminescence (PL) quantum yield for PPA-capped CdSe QDs is larger than that for QDs capped with the analogous sulfur-containing ligand, mercaptopropionic acid (MPA), by a factor of 4 at pH 7, and by up to a factor of 100 under basic conditions. The MPA ligands within MPA-capped QDs oxidize at Eox ∼ +1.7 V versus SCE, whereas cyclic voltammograms of PPA-capped QDs show no discerible oxidation peaks at applied potentials up to +2.5 V versus SCE. The PPA-capped QDs are chemically and colloidally stable for at least 5 days in the dark, even in the presence of O2, and are stable when continuously illuminated for 5 days, when oxygen is excluded and a sacrificial reductant is present to capture photogenerated holes.

Original languageEnglish
Pages (from-to)6716-6723
Number of pages8
JournalChemistry of Materials
Volume28
Issue number18
DOIs
Publication statusPublished - Sep 27 2016

Fingerprint

Cadmium
Sulfur
Semiconductor quantum dots
Photoluminescence
Ligands
Acids
Dimethylformamide
Organophosphonates
Water
Photocatalysis
Reducing Agents
Quantum yield
Encapsulation
Organic solvents
Water quality
Polymers
Oxygen
Imaging techniques
Oxidation

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

Cite this

Organic-to-aqueous phase transfer of cadmium chalcogenide quantum dots using a sulfur-free ligand for enhanced photoluminescence and oxidative stability. / Calzada, Raul; Thompson, Christopher M.; Westmoreland, Dana E.; Edme, Kedy; Weiss, Emily A.

In: Chemistry of Materials, Vol. 28, No. 18, 27.09.2016, p. 6716-6723.

Research output: Contribution to journalArticle

@article{c07946db090a4035845520eecee39353,
title = "Organic-to-aqueous phase transfer of cadmium chalcogenide quantum dots using a sulfur-free ligand for enhanced photoluminescence and oxidative stability",
abstract = "This paper describes a procedure for transferring colloidal CdS and CdSe quantum dots (QDs) from organic solvents to water by exchanging their native hydrophobic ligands for phosphonopropionic acid (PPA) ligands, which bind to the QD surface through the phosphonate group. This method, which uses dimethylformamide as an intermediate transfer solvent, was developed in order to produce high-quality water-soluble QDs with neither a sulfur-containing ligand nor a polymer encapsulation layer, both of which have disadvantages in applications of QDs to photocatalysis and biological imaging. CdS (CdSe) QDs were transferred to water with a 43{\%} (48{\%}) yield using PPA. The photoluminescence (PL) quantum yield for PPA-capped CdSe QDs is larger than that for QDs capped with the analogous sulfur-containing ligand, mercaptopropionic acid (MPA), by a factor of 4 at pH 7, and by up to a factor of 100 under basic conditions. The MPA ligands within MPA-capped QDs oxidize at Eox ∼ +1.7 V versus SCE, whereas cyclic voltammograms of PPA-capped QDs show no discerible oxidation peaks at applied potentials up to +2.5 V versus SCE. The PPA-capped QDs are chemically and colloidally stable for at least 5 days in the dark, even in the presence of O2, and are stable when continuously illuminated for 5 days, when oxygen is excluded and a sacrificial reductant is present to capture photogenerated holes.",
author = "Raul Calzada and Thompson, {Christopher M.} and Westmoreland, {Dana E.} and Kedy Edme and Weiss, {Emily A}",
year = "2016",
month = "9",
day = "27",
doi = "10.1021/acs.chemmater.6b03106",
language = "English",
volume = "28",
pages = "6716--6723",
journal = "Chemistry of Materials",
issn = "0897-4756",
publisher = "American Chemical Society",
number = "18",

}

TY - JOUR

T1 - Organic-to-aqueous phase transfer of cadmium chalcogenide quantum dots using a sulfur-free ligand for enhanced photoluminescence and oxidative stability

AU - Calzada, Raul

AU - Thompson, Christopher M.

AU - Westmoreland, Dana E.

AU - Edme, Kedy

AU - Weiss, Emily A

PY - 2016/9/27

Y1 - 2016/9/27

N2 - This paper describes a procedure for transferring colloidal CdS and CdSe quantum dots (QDs) from organic solvents to water by exchanging their native hydrophobic ligands for phosphonopropionic acid (PPA) ligands, which bind to the QD surface through the phosphonate group. This method, which uses dimethylformamide as an intermediate transfer solvent, was developed in order to produce high-quality water-soluble QDs with neither a sulfur-containing ligand nor a polymer encapsulation layer, both of which have disadvantages in applications of QDs to photocatalysis and biological imaging. CdS (CdSe) QDs were transferred to water with a 43% (48%) yield using PPA. The photoluminescence (PL) quantum yield for PPA-capped CdSe QDs is larger than that for QDs capped with the analogous sulfur-containing ligand, mercaptopropionic acid (MPA), by a factor of 4 at pH 7, and by up to a factor of 100 under basic conditions. The MPA ligands within MPA-capped QDs oxidize at Eox ∼ +1.7 V versus SCE, whereas cyclic voltammograms of PPA-capped QDs show no discerible oxidation peaks at applied potentials up to +2.5 V versus SCE. The PPA-capped QDs are chemically and colloidally stable for at least 5 days in the dark, even in the presence of O2, and are stable when continuously illuminated for 5 days, when oxygen is excluded and a sacrificial reductant is present to capture photogenerated holes.

AB - This paper describes a procedure for transferring colloidal CdS and CdSe quantum dots (QDs) from organic solvents to water by exchanging their native hydrophobic ligands for phosphonopropionic acid (PPA) ligands, which bind to the QD surface through the phosphonate group. This method, which uses dimethylformamide as an intermediate transfer solvent, was developed in order to produce high-quality water-soluble QDs with neither a sulfur-containing ligand nor a polymer encapsulation layer, both of which have disadvantages in applications of QDs to photocatalysis and biological imaging. CdS (CdSe) QDs were transferred to water with a 43% (48%) yield using PPA. The photoluminescence (PL) quantum yield for PPA-capped CdSe QDs is larger than that for QDs capped with the analogous sulfur-containing ligand, mercaptopropionic acid (MPA), by a factor of 4 at pH 7, and by up to a factor of 100 under basic conditions. The MPA ligands within MPA-capped QDs oxidize at Eox ∼ +1.7 V versus SCE, whereas cyclic voltammograms of PPA-capped QDs show no discerible oxidation peaks at applied potentials up to +2.5 V versus SCE. The PPA-capped QDs are chemically and colloidally stable for at least 5 days in the dark, even in the presence of O2, and are stable when continuously illuminated for 5 days, when oxygen is excluded and a sacrificial reductant is present to capture photogenerated holes.

UR - http://www.scopus.com/inward/record.url?scp=84989205121&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84989205121&partnerID=8YFLogxK

U2 - 10.1021/acs.chemmater.6b03106

DO - 10.1021/acs.chemmater.6b03106

M3 - Article

AN - SCOPUS:84989205121

VL - 28

SP - 6716

EP - 6723

JO - Chemistry of Materials

JF - Chemistry of Materials

SN - 0897-4756

IS - 18

ER -