NIR-to-visible upconversion in quantum dots

Via a ligand induced charge transfer state

Noga Meir, Iddo Pinkas, Dan Oron

Research output: Contribution to journalArticle

Abstract

Nanomaterials that possess the ability to upconvert two low-energy photons into a single high-energy photon are of great potential to be useful in a variety of applications. Recent attempts to realize upconversion (UC) in semiconducting quantum dot (QD) systems focused mainly on fabrication of heterostructured colloidal double QDs, or by using colloidal QDs as sensitizers for triplet-triplet annihilation in organic molecules. Here we propose a simplified approach, in which colloidal QDs are coupled to organic thiol ligands and UC is achieved via a charge-transfer state at the molecule-dot interface. We synthesized core/shell CdSe/CdS QDs and replaced their native ligands with thiophenol molecules. The alignment of the molecular HOMO with respect to the QD conduction band resulted in the formation of a new charge-transfer transition from which UC can be promoted. We performed a series of pump-probe experiments and proved the non-linear emission exhibited by these QDs is the result of UC by sequential photon absorption, and further characterized the QD-ligand energy landscape by transient absorption. Finally, we demonstrate that this scheme can also be applied in a QD solid.

Original languageEnglish
Pages (from-to)12153-12161
Number of pages9
JournalRSC Advances
Volume9
Issue number21
DOIs
Publication statusPublished - Jan 1 2019

Fingerprint

Semiconductor quantum dots
Charge transfer
Ligands
Photons
Molecules
Conduction bands
Sulfhydryl Compounds
Nanostructured materials
Pumps
Fabrication
Experiments

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

Cite this

NIR-to-visible upconversion in quantum dots : Via a ligand induced charge transfer state. / Meir, Noga; Pinkas, Iddo; Oron, Dan.

In: RSC Advances, Vol. 9, No. 21, 01.01.2019, p. 12153-12161.

Research output: Contribution to journalArticle

Meir, Noga ; Pinkas, Iddo ; Oron, Dan. / NIR-to-visible upconversion in quantum dots : Via a ligand induced charge transfer state. In: RSC Advances. 2019 ; Vol. 9, No. 21. pp. 12153-12161.
@article{aaee5bf879254431a23d68c6f76e730c,
title = "NIR-to-visible upconversion in quantum dots: Via a ligand induced charge transfer state",
abstract = "Nanomaterials that possess the ability to upconvert two low-energy photons into a single high-energy photon are of great potential to be useful in a variety of applications. Recent attempts to realize upconversion (UC) in semiconducting quantum dot (QD) systems focused mainly on fabrication of heterostructured colloidal double QDs, or by using colloidal QDs as sensitizers for triplet-triplet annihilation in organic molecules. Here we propose a simplified approach, in which colloidal QDs are coupled to organic thiol ligands and UC is achieved via a charge-transfer state at the molecule-dot interface. We synthesized core/shell CdSe/CdS QDs and replaced their native ligands with thiophenol molecules. The alignment of the molecular HOMO with respect to the QD conduction band resulted in the formation of a new charge-transfer transition from which UC can be promoted. We performed a series of pump-probe experiments and proved the non-linear emission exhibited by these QDs is the result of UC by sequential photon absorption, and further characterized the QD-ligand energy landscape by transient absorption. Finally, we demonstrate that this scheme can also be applied in a QD solid.",
author = "Noga Meir and Iddo Pinkas and Dan Oron",
year = "2019",
month = "1",
day = "1",
doi = "10.1039/c9ra01273g",
language = "English",
volume = "9",
pages = "12153--12161",
journal = "RSC Advances",
issn = "2046-2069",
publisher = "Royal Society of Chemistry",
number = "21",

}

TY - JOUR

T1 - NIR-to-visible upconversion in quantum dots

T2 - Via a ligand induced charge transfer state

AU - Meir, Noga

AU - Pinkas, Iddo

AU - Oron, Dan

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Nanomaterials that possess the ability to upconvert two low-energy photons into a single high-energy photon are of great potential to be useful in a variety of applications. Recent attempts to realize upconversion (UC) in semiconducting quantum dot (QD) systems focused mainly on fabrication of heterostructured colloidal double QDs, or by using colloidal QDs as sensitizers for triplet-triplet annihilation in organic molecules. Here we propose a simplified approach, in which colloidal QDs are coupled to organic thiol ligands and UC is achieved via a charge-transfer state at the molecule-dot interface. We synthesized core/shell CdSe/CdS QDs and replaced their native ligands with thiophenol molecules. The alignment of the molecular HOMO with respect to the QD conduction band resulted in the formation of a new charge-transfer transition from which UC can be promoted. We performed a series of pump-probe experiments and proved the non-linear emission exhibited by these QDs is the result of UC by sequential photon absorption, and further characterized the QD-ligand energy landscape by transient absorption. Finally, we demonstrate that this scheme can also be applied in a QD solid.

AB - Nanomaterials that possess the ability to upconvert two low-energy photons into a single high-energy photon are of great potential to be useful in a variety of applications. Recent attempts to realize upconversion (UC) in semiconducting quantum dot (QD) systems focused mainly on fabrication of heterostructured colloidal double QDs, or by using colloidal QDs as sensitizers for triplet-triplet annihilation in organic molecules. Here we propose a simplified approach, in which colloidal QDs are coupled to organic thiol ligands and UC is achieved via a charge-transfer state at the molecule-dot interface. We synthesized core/shell CdSe/CdS QDs and replaced their native ligands with thiophenol molecules. The alignment of the molecular HOMO with respect to the QD conduction band resulted in the formation of a new charge-transfer transition from which UC can be promoted. We performed a series of pump-probe experiments and proved the non-linear emission exhibited by these QDs is the result of UC by sequential photon absorption, and further characterized the QD-ligand energy landscape by transient absorption. Finally, we demonstrate that this scheme can also be applied in a QD solid.

UR - http://www.scopus.com/inward/record.url?scp=85064607594&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85064607594&partnerID=8YFLogxK

U2 - 10.1039/c9ra01273g

DO - 10.1039/c9ra01273g

M3 - Article

VL - 9

SP - 12153

EP - 12161

JO - RSC Advances

JF - RSC Advances

SN - 2046-2069

IS - 21

ER -