Highly Efficient Blue Electroluminescence Using Delayed-Fluorescence Emitters with Large Overlap Density between Luminescent and Ground States

Katsuyuki Shizu, Hiroki Noda, Hiroyuki Tanaka, Masatsugu Taneda, Motoyuki Uejima, Tohru Sato, Kazuyoshi Tanaka, Hironori Kaji, Chihaya Adachi

研究成果: ジャーナルへの寄稿学術誌査読

109 被引用数 (Scopus)

抄録

The use of thermally activated delayed-fluorescence (TADF) allows the realization of highly efficient organic light-emitting diodes (OLEDs) and is a promising alternative to the use of conventional fluorescence and phosphorescence. Recent research interest has focused on blue TADF emitters. In this study, we use quantum mechanics to reveal the relationship between the molecular structures and the photophysical properties of TADF emitters and derive a direction for the molecular design of highly efficient blue TADF emitters. Theoretical analyses show that the luminescence efficiency of TADF emitters largely depends on the overlap density (ρ10) between the electronic wave functions of the ground state and the lowest excited singlet state. By increasing ρ10, we develop an efficient sky-blue TADF emitter material, 9-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9′-phenyl-9H,9′H-3,3′-bicarbazole (BCzT). When doped into a host layer, BCzT produces a high photoluminescence quantum yield of 95.6%. From the transient photoluminescence decays of the doped film, the efficiency of excited triplet state conversion into light is estimated to be 76.2%. An OLED using BCzT as a sky-blue emitter produces a maximum external quantum efficiency (EQE) of 21.7%, which is much higher than the EQE range of conventional fluorescent OLEDs (5-7.5%). The high EQE is a result of the high triplet-to-light conversion efficiency of BCzT. Our material design based on ρ10 distribution provides a rational approach for developing TADF emitters for high-efficiency blue OLEDs.

本文言語英語
ページ(範囲)26283-26289
ページ数7
ジャーナルJournal of Physical Chemistry C
119
47
DOI
出版ステータス出版済み - 11月 25 2015

!!!All Science Journal Classification (ASJC) codes

  • 電子材料、光学材料、および磁性材料
  • エネルギー(全般)
  • 物理化学および理論化学
  • 表面、皮膜および薄膜

フィンガープリント

「Highly Efficient Blue Electroluminescence Using Delayed-Fluorescence Emitters with Large Overlap Density between Luminescent and Ground States」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル