Deep blue phosphorescent organic light-emitting diodes with very high brightness and efficiency

We show that N-heterocyclic carbene Ir(III) complexes can serve as both deep blue emitters and efficient hole-conducting exciton blocking layers

Jaesang Lee; Hsiao-Fan Chen; Thilini Batagoda; Caleb Coburn; Peter I. Djurovich; Mark E. Thompson; Stephen R. Forrest

2015

Key concepts

Scholarcy highlights

  • The combination of both very high brightness and deep blue emission from phosphorescent organic light-emitting diodes is required for both display and lighting applications, yet so far has not been reported
  • A source of this difficulty is the absence of electron/exciton blocking layers that are compatible with the high triplet energy of the deep blue dopant and the high frontier orbital energies of hosts needed to transport charge
  • The N-heterocyclic carbene EBLs enable very high brightness operation, while achieving deep blue emission with colour coordinates of, suitable for most demanding display applications. We find that both the facial and the meridional isomers of the dopant have high efficiencies that arise from the unusual properties of the NHC ligand—that is, the complexes possess a strong metal–ligand bond that destabilizes the non-radiative metal-centred ligand-field states
  • Our results represent an advance in blue-emitting PHOLED architectures and materials combinations that meet the requirements of many critical illumination applications
  • Our results represent an advance in blue-emitting phosphorescent organic light-emitting diodes architectures and materials combinations that meet the requirements of many critical illumination applications

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