Covalently bound hole-injecting nanostructures. Systematics of molecular architecture, thickness, saturation, and electron-blocking characteristics on organic light-emitting diode luminance, turn-on voltage, and quantum efficiency

Qinglan Huang, Guennadi A. Evmenenko, Pulak Dutta, Paul Lee, Neal R. Armstrong, Tobin J Marks

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Abstract

Hole transporting materials are widely used in multilayer organic and polymer light-emitting diodes (OLEDs, PLEDs, respectively) and are indispensable if device electroluminescent response and durability are to be truly optimized. This contribution analyzes the relative effects of tin-doped indium oxide (ITO) anode-hole transporting layer (HTL) contact versus the intrinsic HTL materials properties on OLED performance. Two siloxane-based HTL materials, N,N-bis(p-trichlorosilylpropyl)-naphthalen-1-yl)-N,N-diphenyl-biphenyl-4, 4′-diamine (NPB-Si2) and 4,4′-bis[(p- trichlorosilylpropylphenyl)phenylamino]biphenyl (TPD-Si2), are designed and synthesized. They have the same hole transporting triarylamine cores as conventional HTL materials such as 1,4-bis(1-naphthylphenylamino) biphenyl (NPB) and N,N-diphenyl-N,N-bis(3-methylphenyl)-1,1-biphenyl)-4,4- diamine (TPD), respectively. However, they covalently bind to the ITO anode, forming anode-HTL contacts that are intrinsically different from those of the anode to TPD and NPB. Applied to archetypical tris(8-hydroxyquinolato) aluminum(III) (Alq)-based OLEDs as (1) the sole HTLs or (2) anode-NPB HTL interlayers, NPB-Si2 and TPD-Si2 enhance device electroluminescent response significantly versus comparable devices based on NPB alone. In the first case, OLEDs with 36 000 cd/m2 luminance, 1.6% forward external quantum efficiency (ηext), and 5 V turn-on voltages are achieved, affording a 250% increase in luminance and ∼50% reduction in turn-on voltage, as compared to NPB-based devices. In the second case, even more dramatic enhancement is observed (64 000 cd/m2 luminance; 2.3% ηext; turn-on voltages as low as 3.5 V). The importance of the anode-HTL material contact is further explored by replacing NPB with saturated hydrocarbon siloxane monolayers that covalently bind to the anode, without sacrificing device performance (30 000 cd/m2 luminance; 2.0% ηext; 4.0 V turn-on voltage). These results suggest new strategies for developing OLED hole transporting structures.

Original languageEnglish
Pages (from-to)10227-10242
Number of pages16
JournalJournal of the American Chemical Society
Volume127
Issue number29
DOIs
Publication statusPublished - Jul 27 2005

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Nanostructures
Organic light emitting diodes (OLED)
Quantum efficiency
Luminance
Anodes
Electrons
Light
Temperature programmed desorption
Electric potential
Electrodes
Luminescent devices
Equipment and Supplies
Siloxanes
Diamines
diphenyl
Indium
Tin
Light emitting diodes
Monolayers
Materials properties

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

@article{461150b9cd70461382927db61e255acb,
title = "Covalently bound hole-injecting nanostructures. Systematics of molecular architecture, thickness, saturation, and electron-blocking characteristics on organic light-emitting diode luminance, turn-on voltage, and quantum efficiency",
abstract = "Hole transporting materials are widely used in multilayer organic and polymer light-emitting diodes (OLEDs, PLEDs, respectively) and are indispensable if device electroluminescent response and durability are to be truly optimized. This contribution analyzes the relative effects of tin-doped indium oxide (ITO) anode-hole transporting layer (HTL) contact versus the intrinsic HTL materials properties on OLED performance. Two siloxane-based HTL materials, N,N-bis(p-trichlorosilylpropyl)-naphthalen-1-yl)-N,N-diphenyl-biphenyl-4, 4′-diamine (NPB-Si2) and 4,4′-bis[(p- trichlorosilylpropylphenyl)phenylamino]biphenyl (TPD-Si2), are designed and synthesized. They have the same hole transporting triarylamine cores as conventional HTL materials such as 1,4-bis(1-naphthylphenylamino) biphenyl (NPB) and N,N-diphenyl-N,N-bis(3-methylphenyl)-1,1-biphenyl)-4,4- diamine (TPD), respectively. However, they covalently bind to the ITO anode, forming anode-HTL contacts that are intrinsically different from those of the anode to TPD and NPB. Applied to archetypical tris(8-hydroxyquinolato) aluminum(III) (Alq)-based OLEDs as (1) the sole HTLs or (2) anode-NPB HTL interlayers, NPB-Si2 and TPD-Si2 enhance device electroluminescent response significantly versus comparable devices based on NPB alone. In the first case, OLEDs with 36 000 cd/m2 luminance, 1.6{\%} forward external quantum efficiency (ηext), and 5 V turn-on voltages are achieved, affording a 250{\%} increase in luminance and ∼50{\%} reduction in turn-on voltage, as compared to NPB-based devices. In the second case, even more dramatic enhancement is observed (64 000 cd/m2 luminance; 2.3{\%} ηext; turn-on voltages as low as 3.5 V). The importance of the anode-HTL material contact is further explored by replacing NPB with saturated hydrocarbon siloxane monolayers that covalently bind to the anode, without sacrificing device performance (30 000 cd/m2 luminance; 2.0{\%} ηext; 4.0 V turn-on voltage). These results suggest new strategies for developing OLED hole transporting structures.",
author = "Qinglan Huang and Evmenenko, {Guennadi A.} and Pulak Dutta and Paul Lee and Armstrong, {Neal R.} and Marks, {Tobin J}",
year = "2005",
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pages = "10227--10242",
journal = "Journal of the American Chemical Society",
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publisher = "American Chemical Society",
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TY - JOUR

T1 - Covalently bound hole-injecting nanostructures. Systematics of molecular architecture, thickness, saturation, and electron-blocking characteristics on organic light-emitting diode luminance, turn-on voltage, and quantum efficiency

AU - Huang, Qinglan

AU - Evmenenko, Guennadi A.

AU - Dutta, Pulak

AU - Lee, Paul

AU - Armstrong, Neal R.

AU - Marks, Tobin J

PY - 2005/7/27

Y1 - 2005/7/27

N2 - Hole transporting materials are widely used in multilayer organic and polymer light-emitting diodes (OLEDs, PLEDs, respectively) and are indispensable if device electroluminescent response and durability are to be truly optimized. This contribution analyzes the relative effects of tin-doped indium oxide (ITO) anode-hole transporting layer (HTL) contact versus the intrinsic HTL materials properties on OLED performance. Two siloxane-based HTL materials, N,N-bis(p-trichlorosilylpropyl)-naphthalen-1-yl)-N,N-diphenyl-biphenyl-4, 4′-diamine (NPB-Si2) and 4,4′-bis[(p- trichlorosilylpropylphenyl)phenylamino]biphenyl (TPD-Si2), are designed and synthesized. They have the same hole transporting triarylamine cores as conventional HTL materials such as 1,4-bis(1-naphthylphenylamino) biphenyl (NPB) and N,N-diphenyl-N,N-bis(3-methylphenyl)-1,1-biphenyl)-4,4- diamine (TPD), respectively. However, they covalently bind to the ITO anode, forming anode-HTL contacts that are intrinsically different from those of the anode to TPD and NPB. Applied to archetypical tris(8-hydroxyquinolato) aluminum(III) (Alq)-based OLEDs as (1) the sole HTLs or (2) anode-NPB HTL interlayers, NPB-Si2 and TPD-Si2 enhance device electroluminescent response significantly versus comparable devices based on NPB alone. In the first case, OLEDs with 36 000 cd/m2 luminance, 1.6% forward external quantum efficiency (ηext), and 5 V turn-on voltages are achieved, affording a 250% increase in luminance and ∼50% reduction in turn-on voltage, as compared to NPB-based devices. In the second case, even more dramatic enhancement is observed (64 000 cd/m2 luminance; 2.3% ηext; turn-on voltages as low as 3.5 V). The importance of the anode-HTL material contact is further explored by replacing NPB with saturated hydrocarbon siloxane monolayers that covalently bind to the anode, without sacrificing device performance (30 000 cd/m2 luminance; 2.0% ηext; 4.0 V turn-on voltage). These results suggest new strategies for developing OLED hole transporting structures.

AB - Hole transporting materials are widely used in multilayer organic and polymer light-emitting diodes (OLEDs, PLEDs, respectively) and are indispensable if device electroluminescent response and durability are to be truly optimized. This contribution analyzes the relative effects of tin-doped indium oxide (ITO) anode-hole transporting layer (HTL) contact versus the intrinsic HTL materials properties on OLED performance. Two siloxane-based HTL materials, N,N-bis(p-trichlorosilylpropyl)-naphthalen-1-yl)-N,N-diphenyl-biphenyl-4, 4′-diamine (NPB-Si2) and 4,4′-bis[(p- trichlorosilylpropylphenyl)phenylamino]biphenyl (TPD-Si2), are designed and synthesized. They have the same hole transporting triarylamine cores as conventional HTL materials such as 1,4-bis(1-naphthylphenylamino) biphenyl (NPB) and N,N-diphenyl-N,N-bis(3-methylphenyl)-1,1-biphenyl)-4,4- diamine (TPD), respectively. However, they covalently bind to the ITO anode, forming anode-HTL contacts that are intrinsically different from those of the anode to TPD and NPB. Applied to archetypical tris(8-hydroxyquinolato) aluminum(III) (Alq)-based OLEDs as (1) the sole HTLs or (2) anode-NPB HTL interlayers, NPB-Si2 and TPD-Si2 enhance device electroluminescent response significantly versus comparable devices based on NPB alone. In the first case, OLEDs with 36 000 cd/m2 luminance, 1.6% forward external quantum efficiency (ηext), and 5 V turn-on voltages are achieved, affording a 250% increase in luminance and ∼50% reduction in turn-on voltage, as compared to NPB-based devices. In the second case, even more dramatic enhancement is observed (64 000 cd/m2 luminance; 2.3% ηext; turn-on voltages as low as 3.5 V). The importance of the anode-HTL material contact is further explored by replacing NPB with saturated hydrocarbon siloxane monolayers that covalently bind to the anode, without sacrificing device performance (30 000 cd/m2 luminance; 2.0% ηext; 4.0 V turn-on voltage). These results suggest new strategies for developing OLED hole transporting structures.

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