Siloxy Group-Induced Highly Efficient Room Temperature Phosphorescence with Long Lifetime

Masaki Shimizu, Ryosuke Shigitani, Masaki Nakatani, Keiko Kuwabara, Yusuke Miyake, Kunihiko Tajima, Hayato Sakai, Taku Hasobe

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

The design and development of organic phosphors that exhibit efficient emission at room temperature but do not contain precious metals such as iridium and platinum have attracted increasing attention. We report herein highly efficient green phosphorescence-emitting 1,4-dibenzoyl-2,5-bis(siloxy)benzene crystals in air at room temperature. Remarkable luminescence quantum yields of 0.46 to 0.64 and long lifetimes ranging from 76.0 to 98.3 ms were observed. X-ray diffraction analysis of the single crystals revealed that there were several intermolecular interactions causing suppression of intramolecular motion, thereby minimizing nonradiative decay of the triplet excited state. Comparison with the corresponding 2,5-bis(dimethylphenylsilylmethyl) and 2,5-bis(trimethylsilyl) derivatives revealed that the siloxy groups are essential for efficient room temperature phosphorescence. Density functional calculations suggested that σ-n conjugation was operative in the siloxy moieties. Electron spin resonance measurement indicated that the radiative process included generation of the triplet diradical species, whose electron distribution was very similar to that of naphthalene. The present study largely expands the possibilities for the molecular design of precious metal- and halogen-free organic phosphors exhibiting efficient room temperature phosphorescence.

Original languageEnglish
Pages (from-to)11631-11639
Number of pages9
JournalJournal of Physical Chemistry C
Volume120
Issue number21
DOIs
Publication statusPublished - 2016 Jun 2

ASJC Scopus subject areas

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

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