Nature of highly efficient thermally activated delayed fluorescence in organic light-emitting diode emitters: Nonadiabatic effect between excited states

Xian Kai Chen, Shou Feng Zhang, Jian Xun Fan, Ai Min Ren

Research output: Contribution to journalArticlepeer-review

114 Citations (Scopus)

Abstract

The discovery and utilization of metal-free organic emitters with thermally activated delayed fluorescence (TADF) is a huge breakthrough toward high-performance and low-cost organic light-emitting diodes. Time-dependent second-order perturbation theory including spin-orbit and nonadiabatic couplings, combined with time-dependent density functional theory, is employed to reveal the nature of highly efficient TADF in pure organic emitters. Our results demonstrate that except energy gaps between the lowest singlet (S1) and triplet (T1) excited states the nonadiabatic effect between low-lying excited states should play a key role in the T1 S1 upconversion for TADF emitters, especially donor-acceptor-donor (D-A-D) molecules. We not only clarify the reason why D-A-D molecules with large S1-T1 energy gaps show efficient TADF but also explain the experimental observation that D-A-D-type compounds with S1-T1 gaps close to those of their D-A-shape counterparts display more efficient T1 S1 upconversion.

Original languageEnglish
Pages (from-to)9728-9733
Number of pages6
JournalJournal of Physical Chemistry C
Volume119
Issue number18
DOIs
Publication statusPublished - May 7 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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