Anode interfacial engineering approaches to enhancing anode/hole transport layer interfacial stability and charge injection efficiency in organic light-emitting diodes

Ji Cui, Qinglan Huang, Jonathan C G Veinot, He Yan, Qingwu Wang, Geoffrey R. Hutchison, Andrew G. Richter, Guennadi Evmenenko, Pulak Dutta, Tobin J Marks

Research output: Contribution to journalArticle

100 Citations (Scopus)

Abstract

The integrity of anode/organic interfacial contact is shown to be crucial to the performance and stability of archetypical small molecule organic light-emitting diodes (OLEDs). In this contribution, vapor-deposited lipophilic, hole-transporting 1,4-bis(phenyl-m-tolylamino)biphenyl (TPD) and 1,4-bis(1-naphthylphenylamino)biphenyl (NPB) thin films are shown to undergo decohesion on ITO anode surfaces under mild heating. An effective approach to ameliorate such interfacial decohesion is introduction, via self-assembly or spin-coating, of covalently bound N(p-C6H4CH2CH2CH2 SiCl3)3 (TAA)- and 4,4′-bis[(p-trichlorosilylpropylphenyl)phenylamino]biphenyl (TPD-Si2)-derived adhesion/injection layers at the anode/hole transport layer interface. The resulting angstrom-scale hole transport layers prevent decohesion of vapor-deposited hole transport layers and significantly enhance OLED hole injection fluence. OLEDs fabricated with these modified interfaces exhibit appreciably reduced turn-on voltages, considerably higher luminous intensities, and enhanced thermal robustness versus bare ITO-based control devices. Spin-coated, cross-linked TPD-Si2 films, in particular, prove to be superior to conventional ITO functionalization interlayers, including copper phthalocyanine, in this regard. The present ITO-functionalized devices achieve maximum external forward quantum efficiencies as high as 1.2% and a luminous level of 15 000 cd/m2 in simple ITO/interlayer/HTL/Alq/Al heterostructures. We also show that Cu(Pc) interlayers actually suppress, rather than enhance, hole injection and template crystallization of vapor-deposited TPD and NPB at modest temperatures, resulting in poor OLED thermal stability.

Original languageEnglish
Pages (from-to)9958-9970
Number of pages13
JournalLangmuir
Volume18
Issue number25
DOIs
Publication statusPublished - Dec 10 2002

Fingerprint

Charge injection
Organic light emitting diodes (OLED)
Temperature programmed desorption
ITO (semiconductors)
Anodes
anodes
light emitting diodes
engineering
injection
Vapors
interlayers
vapors
Spin coating
Crystallization
Quantum efficiency
Self assembly
Heterojunctions
Thermodynamic stability
Adhesion
control equipment

ASJC Scopus subject areas

  • Colloid and Surface Chemistry
  • Physical and Theoretical Chemistry

Cite this

Anode interfacial engineering approaches to enhancing anode/hole transport layer interfacial stability and charge injection efficiency in organic light-emitting diodes. / Cui, Ji; Huang, Qinglan; Veinot, Jonathan C G; Yan, He; Wang, Qingwu; Hutchison, Geoffrey R.; Richter, Andrew G.; Evmenenko, Guennadi; Dutta, Pulak; Marks, Tobin J.

In: Langmuir, Vol. 18, No. 25, 10.12.2002, p. 9958-9970.

Research output: Contribution to journalArticle

Cui, Ji ; Huang, Qinglan ; Veinot, Jonathan C G ; Yan, He ; Wang, Qingwu ; Hutchison, Geoffrey R. ; Richter, Andrew G. ; Evmenenko, Guennadi ; Dutta, Pulak ; Marks, Tobin J. / Anode interfacial engineering approaches to enhancing anode/hole transport layer interfacial stability and charge injection efficiency in organic light-emitting diodes. In: Langmuir. 2002 ; Vol. 18, No. 25. pp. 9958-9970.
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AU - Yan, He

AU - Wang, Qingwu

AU - Hutchison, Geoffrey R.

AU - Richter, Andrew G.

AU - Evmenenko, Guennadi

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