Reduced geminate recombination in iridium-based electrophosphorescent materials

R. J. Holmes; S. R. Forrest; T. Sajoto; A. Tamayo; P. I. Djurovich; M. E. Thompson

doi:10.1016/j.orgel.2006.03.009

Reduced geminate recombination in iridium-based electrophosphorescent materials

R. J. Holmes, S. R. Forrest, T. Sajoto, A. Tamayo, P. I. Djurovich, M. E. Thompson

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Abstract

We demonstrate reduced geminate recombination of excitons in electrophosphorescent organic light emitting devices using the green phosphor fac-tris(1-(9′,9′-dimethyl-2′-fluorenyl)pyrazolato,N,C²)iridium(III). At low phosphor doping concentrations (<20 wt.%) in a N,N′-dicarbazolyl-3,5-benzene host, transient electroluminescence spectra show no bimolecular quenching at the highest excitation densities used. At higher doping concentrations (>60 wt.%), the transient decay reflects the presence of phosphor molecular aggregates. The roll-off in external quantum efficiency at high current densities is attributed to the field-assisted dissociation of charge pairs prior to exciton formation.

Original language	English (US)
Pages (from-to)	163-172
Number of pages	10
Journal	Organic Electronics
Volume	7
Issue number	3
DOIs	https://doi.org/10.1016/j.orgel.2006.03.009
State	Published - Jun 2006
Externally published	Yes

Bibliographical note

Funding Information:
This work was partially supported by the Air Force Office of Scientific Research, the Department of Energy Solid State Lighting Program, and Universal Display Corporation.

Keywords

Exciton quenching
Organic light emitting devices
Phosphorescence

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title = "Reduced geminate recombination in iridium-based electrophosphorescent materials",

abstract = "We demonstrate reduced geminate recombination of excitons in electrophosphorescent organic light emitting devices using the green phosphor fac-tris(1-(9′,9′-dimethyl-2′-fluorenyl)pyrazolato,N,C2)iridium(III). At low phosphor doping concentrations (<20 wt.%) in a N,N′-dicarbazolyl-3,5-benzene host, transient electroluminescence spectra show no bimolecular quenching at the highest excitation densities used. At higher doping concentrations (>60 wt.%), the transient decay reflects the presence of phosphor molecular aggregates. The roll-off in external quantum efficiency at high current densities is attributed to the field-assisted dissociation of charge pairs prior to exciton formation.",

keywords = "Exciton quenching, Organic light emitting devices, Phosphorescence",

author = "Holmes, {R. J.} and Forrest, {S. R.} and T. Sajoto and A. Tamayo and Djurovich, {P. I.} and Thompson, {M. E.}",

note = "Funding Information: This work was partially supported by the Air Force Office of Scientific Research, the Department of Energy Solid State Lighting Program, and Universal Display Corporation. ",

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volume = "7",

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AU - Holmes, R. J.

AU - Forrest, S. R.

AU - Sajoto, T.

AU - Tamayo, A.

AU - Djurovich, P. I.

AU - Thompson, M. E.

N1 - Funding Information: This work was partially supported by the Air Force Office of Scientific Research, the Department of Energy Solid State Lighting Program, and Universal Display Corporation.

PY - 2006/6

Y1 - 2006/6

N2 - We demonstrate reduced geminate recombination of excitons in electrophosphorescent organic light emitting devices using the green phosphor fac-tris(1-(9′,9′-dimethyl-2′-fluorenyl)pyrazolato,N,C2)iridium(III). At low phosphor doping concentrations (<20 wt.%) in a N,N′-dicarbazolyl-3,5-benzene host, transient electroluminescence spectra show no bimolecular quenching at the highest excitation densities used. At higher doping concentrations (>60 wt.%), the transient decay reflects the presence of phosphor molecular aggregates. The roll-off in external quantum efficiency at high current densities is attributed to the field-assisted dissociation of charge pairs prior to exciton formation.

AB - We demonstrate reduced geminate recombination of excitons in electrophosphorescent organic light emitting devices using the green phosphor fac-tris(1-(9′,9′-dimethyl-2′-fluorenyl)pyrazolato,N,C2)iridium(III). At low phosphor doping concentrations (<20 wt.%) in a N,N′-dicarbazolyl-3,5-benzene host, transient electroluminescence spectra show no bimolecular quenching at the highest excitation densities used. At higher doping concentrations (>60 wt.%), the transient decay reflects the presence of phosphor molecular aggregates. The roll-off in external quantum efficiency at high current densities is attributed to the field-assisted dissociation of charge pairs prior to exciton formation.

KW - Exciton quenching

KW - Organic light emitting devices

KW - Phosphorescence

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JO - Organic Electronics

JF - Organic Electronics

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ER -

Reduced geminate recombination in iridium-based electrophosphorescent materials

Abstract

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Keywords

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