Chain-length dependence of singlet and triplet exciton formation rates in organic light-emitting diodes

David Beljonne*, Aijun Ye, Zhigang Shuai, Jean-Luc Bredas

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

92 Scopus citations

Abstract

The operation and efficiencies of molecular or polymer organic light-emitting diodes depend on the nature of the excited species that are formed. The lowest Singlet and triplet excitons display different characteristics that impact on the quantum yields achievable in the devices. Here, by performing correlated quantum-chemical calculations that account for both the electronic couplings and energetics of the charge-recombination process from a pair of positive and negative polarons into singlet and triplet excitons, we show that the formation rates for singlet over triplet excitons vary with chain length and favor singlet excitons in longer chains. Thus, in polymer devices, the resulting singlet/triplet fraction can significantly exceed the spin-statistical limit.

Original languageEnglish (US)
Pages (from-to)684-692
Number of pages9
JournalAdvanced Functional Materials
Volume14
Issue number7
DOIs
StatePublished - Jul 1 2004

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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