Phosphorescent iridium(III) cored dendrimers for light-emitting displays

J. C. Ribierre, S. V. Staton, P. L. Burn, I. D.W. Samuel

Research output: Contribution to journalConference article

1 Citation (Scopus)

Abstract

Solution-processable electrophosphorescent dendrimers are an emerging class of materials for highly efficient light-emitting diodes. Here, we report time-resolved photoluminescence measurements in a fac-tris(2-phenylpyridyl) iridium(III) [Ir(ppy)3]-cored dendrimer in neat film and blended into a 4,4'-bis(N-carbazolyl)biphenyl (CBP) host. Our results identify the existence of a photodegradation process that occurs in solution prior to processing, which significantly affects the photoluminescence kinetics of the films and leads to lower external quantum efficiencies of solution-processed phosphorescent dendrimer light-emitting displays. In parallel, we studied the triplet-triplet exciton annihilation processes in these materials from the photoluminescence decays measured at various excitation densities. From the values of the annihilation rates, we calculated the triplet exciton diffusion lengths and estimated the limiting current densities above which annihilation would dominate in phosphorescent dendrimer light-emitting devices. The results show that the triplet exciton diffusion length is small (<15 nm) in phosphorescent dendrimers and that exciton diffusion becomes still slower in the blends, which can be interpreted by the intermolecular spacing between the phosphorescent emitters being increased, thus reducing the annihilation rate.

Original languageEnglish
Article number63330H
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume6333
DOIs
Publication statusPublished - Dec 1 2006
EventOrganic Ligh Emitting Materials and Devices X - San Diego, CA, United States
Duration: Aug 13 2006Aug 16 2006

Fingerprint

Dendrimers
Iridium
dendrimers
iridium
Exciton
Display
Annihilation
Excitons
Display devices
Photoluminescence
excitons
diffusion length
photoluminescence
Quantum Efficiency
Photodegradation
Quantum efficiency
Diode
Spacing
Light emitting diodes
quantum efficiency

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Cite this

Phosphorescent iridium(III) cored dendrimers for light-emitting displays. / Ribierre, J. C.; Staton, S. V.; Burn, P. L.; Samuel, I. D.W.

In: Proceedings of SPIE - The International Society for Optical Engineering, Vol. 6333, 63330H, 01.12.2006.

Research output: Contribution to journalConference article

@article{63b2f048cf6e413c8d084fd62cbd91a8,
title = "Phosphorescent iridium(III) cored dendrimers for light-emitting displays",
abstract = "Solution-processable electrophosphorescent dendrimers are an emerging class of materials for highly efficient light-emitting diodes. Here, we report time-resolved photoluminescence measurements in a fac-tris(2-phenylpyridyl) iridium(III) [Ir(ppy)3]-cored dendrimer in neat film and blended into a 4,4'-bis(N-carbazolyl)biphenyl (CBP) host. Our results identify the existence of a photodegradation process that occurs in solution prior to processing, which significantly affects the photoluminescence kinetics of the films and leads to lower external quantum efficiencies of solution-processed phosphorescent dendrimer light-emitting displays. In parallel, we studied the triplet-triplet exciton annihilation processes in these materials from the photoluminescence decays measured at various excitation densities. From the values of the annihilation rates, we calculated the triplet exciton diffusion lengths and estimated the limiting current densities above which annihilation would dominate in phosphorescent dendrimer light-emitting devices. The results show that the triplet exciton diffusion length is small (<15 nm) in phosphorescent dendrimers and that exciton diffusion becomes still slower in the blends, which can be interpreted by the intermolecular spacing between the phosphorescent emitters being increased, thus reducing the annihilation rate.",
author = "Ribierre, {J. C.} and Staton, {S. V.} and Burn, {P. L.} and Samuel, {I. D.W.}",
year = "2006",
month = "12",
day = "1",
doi = "10.1117/12.683380",
language = "English",
volume = "6333",
journal = "Proceedings of SPIE - The International Society for Optical Engineering",
issn = "0277-786X",
publisher = "SPIE",

}

TY - JOUR

T1 - Phosphorescent iridium(III) cored dendrimers for light-emitting displays

AU - Ribierre, J. C.

AU - Staton, S. V.

AU - Burn, P. L.

AU - Samuel, I. D.W.

PY - 2006/12/1

Y1 - 2006/12/1

N2 - Solution-processable electrophosphorescent dendrimers are an emerging class of materials for highly efficient light-emitting diodes. Here, we report time-resolved photoluminescence measurements in a fac-tris(2-phenylpyridyl) iridium(III) [Ir(ppy)3]-cored dendrimer in neat film and blended into a 4,4'-bis(N-carbazolyl)biphenyl (CBP) host. Our results identify the existence of a photodegradation process that occurs in solution prior to processing, which significantly affects the photoluminescence kinetics of the films and leads to lower external quantum efficiencies of solution-processed phosphorescent dendrimer light-emitting displays. In parallel, we studied the triplet-triplet exciton annihilation processes in these materials from the photoluminescence decays measured at various excitation densities. From the values of the annihilation rates, we calculated the triplet exciton diffusion lengths and estimated the limiting current densities above which annihilation would dominate in phosphorescent dendrimer light-emitting devices. The results show that the triplet exciton diffusion length is small (<15 nm) in phosphorescent dendrimers and that exciton diffusion becomes still slower in the blends, which can be interpreted by the intermolecular spacing between the phosphorescent emitters being increased, thus reducing the annihilation rate.

AB - Solution-processable electrophosphorescent dendrimers are an emerging class of materials for highly efficient light-emitting diodes. Here, we report time-resolved photoluminescence measurements in a fac-tris(2-phenylpyridyl) iridium(III) [Ir(ppy)3]-cored dendrimer in neat film and blended into a 4,4'-bis(N-carbazolyl)biphenyl (CBP) host. Our results identify the existence of a photodegradation process that occurs in solution prior to processing, which significantly affects the photoluminescence kinetics of the films and leads to lower external quantum efficiencies of solution-processed phosphorescent dendrimer light-emitting displays. In parallel, we studied the triplet-triplet exciton annihilation processes in these materials from the photoluminescence decays measured at various excitation densities. From the values of the annihilation rates, we calculated the triplet exciton diffusion lengths and estimated the limiting current densities above which annihilation would dominate in phosphorescent dendrimer light-emitting devices. The results show that the triplet exciton diffusion length is small (<15 nm) in phosphorescent dendrimers and that exciton diffusion becomes still slower in the blends, which can be interpreted by the intermolecular spacing between the phosphorescent emitters being increased, thus reducing the annihilation rate.

UR - http://www.scopus.com/inward/record.url?scp=33846994087&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33846994087&partnerID=8YFLogxK

U2 - 10.1117/12.683380

DO - 10.1117/12.683380

M3 - Conference article

AN - SCOPUS:33846994087

VL - 6333

JO - Proceedings of SPIE - The International Society for Optical Engineering

JF - Proceedings of SPIE - The International Society for Optical Engineering

SN - 0277-786X

M1 - 63330H

ER -