Highly efficient organic light-emitting diodes from delayed fluorescence

Hiroki Uoyama, Kenichi Goushi, Katsuyuki Shizu, Hiroko Nomura, Chihaya Adachi

Research output: Contribution to journalArticlepeer-review

3427 Citations (Scopus)

Abstract

The inherent flexibility afforded by molecular design has accelerated the development of a wide variety of organic semiconductors over the past two decades. In particular, great advances have been made in the development of materials for organic light-emitting diodes (OLEDs), from early devices based on fluorescent molecules to those using phosphorescent molecules. In OLEDs, electrically injected charge carriers recombine to form singlet and triplet excitons in a 1:3 ratio; the use of phosphorescent metal-organic complexes exploits the normally non-radiative triplet excitons and so enhances the overall electroluminescence efficiency. Here we report a class of metal-free organic electroluminescent molecules in which the energy gap between the singlet and triplet excited states is minimized by design, thereby promoting highly efficient spin up-conversion from non-radiative triplet states to radiative singlet states while maintaining high radiative decay rates, of more than 10 6 decays per second. In other words, these molecules harness both singlet and triplet excitons for light emission through fluorescence decay channels, leading to an intrinsic fluorescence efficiency in excess of 90 per cent and a very high external electroluminescence efficiency, of more than 19 per cent, which is comparable to that achieved in high-efficiency phosphorescence-based OLEDs.

Original languageEnglish
Pages (from-to)234-238
Number of pages5
JournalNature
Volume492
Issue number7428
DOIs
Publication statusPublished - Dec 13 2012

All Science Journal Classification (ASJC) codes

  • General

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