High stability and luminescence efficiency in donor–acceptor neutral radicals not following the Aufbau principle

Haoqing Guo, Qiming Peng, Xian Kai Chen, Qinying Gu, Shengzhi Dong, Emrys W. Evans, Alexander J. Gillett, Xin Ai, Ming Zhang, Dan Credgington, Veaceslav Coropceanu, Richard H. Friend, Jean Luc Brédas, Feng Li

Research output: Contribution to journalArticlepeer-review

169 Scopus citations


With their unusual electronic structures, organic radical molecules display luminescence properties potentially relevant to lighting applications; yet, their luminescence quantum yield and stability lag behind those of other organic emitters. Here, we designed donor–acceptor neutral radicals based on an electron-poor perchlorotriphenylmethyl or tris(2,4,6-trichlorophenyl)methyl radical moiety combined with different electron-rich groups. Experimental and quantum-chemical studies demonstrate that the molecules do not follow the Aufbau principle: the singly occupied molecular orbital is found to lie below the highest (doubly) occupied molecular orbital. These donor–acceptor radicals have a strong emission yield (up to 54%) and high photostability, with estimated half-lives reaching up to several months under pulsed ultraviolet laser irradiation. Organic light-emitting diodes based on such a radical emitter show deep-red/near-infrared emission with a maximal external quantum efficiency of 5.3%. Our results provide a simple molecular-design strategy for stable, highly luminescent radicals with non-Aufbau electronic structures.

Original languageEnglish (US)
Pages (from-to)977-984
Number of pages8
JournalNature materials
Issue number9
StatePublished - Sep 1 2019
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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