Electrogenerated chemiluminescence from derivatives of aluminum quinolate and quinacridones: Cross-reactions with triarylamines lead to singlet emission through triplet-triplet annihilation pathways

E. M. Gross, J. D. Anderson, A. F. Slaterbeck, S. Thayumanavan, S. Barlow, Y. Zhang, S. R. Marder, H. K. Hall, M. Flore Nabor, J. F. Wang, E. A. Mash, N. R. Armstrong, R. M. Wightman

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Abstract

Solution electrogenerated chemiluminescence (ECL) was evaluated for molecules of interest for organic light-emitting diodes (OLEDs), using high- frequency voltage pulses at a microelectrode Radical cations of different energies were electrogenerated from a series of triarylamine hole-transport materials (x-TPD), in the presence of radical anions of a high electron affinity sulfonamide derivative of tris(8-hydroxyquinoline)aluminum (Al(qs)3), or a bis(isoamyl) derivative of quinacridone (DIQA). The resultant emission was from the excited singlet states 1Al(qs)3* or 1DIQA*, the same excited state produced in OLEDs based on these molecules. In solution, the majority of the reaction pairs had insufficient energy to populate 1Al(qs)3* or 1DIQA* directly, but could form the triplet states 3Al(qs)3* or 3DIQA*. The reaction order and the temporal response of the emission were consistent with subsequent formation of the excited singlet states via triplet-triplet annihilation (TTA). For reactions with a low excess Gibbs free energy to form the triplet state (Δ(T)G), the efficiency increased exponentially with an increase in driving force (increase in oxidation potential of x-TPD), then reached a plateau. At the maximum, the efficiencies for formation of 1Al(qs)3* or 1DIQA* via the TTA route reach as high as a few percent. The computed energetics of these reactions suggest that similar light-producing electroluminescent reactions, proceeding via triplet formation, could also occur in condensed phase organic thin films.

Original languageEnglish (US)
Pages (from-to)4972-4979
Number of pages8
JournalJournal of the American Chemical Society
Volume122
Issue number20
DOIs
StatePublished - May 24 2000
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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