Elucidating the Spatial Arrangement of Emitter Molecules in Organic Light-Emitting Diode Films

Claire Tonnelé, Martin Stroet, Bertrand Caron, Andrew J Clulow, Ravi C R Nagiri, Alpeshkumar K. Malde, Paul L. Burn, Ian R. Gentle, Alan E. Mark, Benjamin J. Powell

Research output: Contribution to journalArticleResearchpeer-review

26 Citations (Scopus)

Abstract

The effect of varying the emitter concentration on the structural properties of an archetypal phosphorescent blend consisting of 4,4′-bis(N-carbazolyl)biphenyl and tris(2-phenylpyridyl)iridium(III) has been investigated using non-equilibrium molecular dynamics (MD) simulations that mimic the process of vacuum deposition. By comparison with reflectometry measurements, we show that the simulations provide an accurate model of the average density of such films. The emitter molecules were found not to be evenly distributed throughout film, but rather they can form networks that provide charge and/or energy migration pathways, even at emitter concentrations as low as ≈5 weight percent. At slightly higher concentrations, percolated networks form that span the entire system. While such networks would give improved charge transport, they could also lead to more non-radiative pathways for the emissive state and a resultant loss of efficiency.

Original languageEnglish
Pages (from-to)8402-8406
Number of pages5
JournalAngewandte Chemie - International Edition
Volume56
Issue number29
DOIs
Publication statusPublished - 2017
Externally publishedYes

Keywords

  • Connectivity
  • Evaporation
  • Ir(ppy):CBP blends
  • Morphology
  • OLEDs

Cite this