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Full‐Color Delayed Fluorescence Materials Based on Wedge‐Shaped Phthalonitriles and Dicyanopyrazines: Systematic Design, Tunable Photophysical Properties, and OLED Performance
Author(s) -
Park In Seob,
Lee Sae Youn,
Adachi Chihaya,
Yasuda Takuma
Publication year - 2016
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201505106
Subject(s) - oled , materials science , electroluminescence , phthalonitrile , optoelectronics , acceptor , fluorescence , excited state , singlet state , luminescence , photochemistry , nanotechnology , phthalocyanine , optics , chemistry , layer (electronics) , atomic physics , condensed matter physics , physics
Purely organic light‐emitting materials, which can harvest both singlet and triplet excited states to offer high electron‐to‐photon conversion efficiencies, are essential for the realization of high‐performance organic light‐emitting diodes (OLEDs) without using precious metal elements. Donor–acceptor architectures with an intramolecular charge‐transfer excited state have been proved to be a promising system for achieving these requirements through a mechanism of thermally activated delayed fluorescence (TADF). Here, luminescent wedge‐shaped molecules, which comprise a central phthalonitrile or 2,3‐dicyanopyrazine acceptor core coupled with various donor units, are reported as TADF emitters. This set of materials allows systematic fine‐tuning of the band gap and exhibits TADF emissions that cover the entire visible range from blue to red. Full‐color TADF‐OLEDs with high maximum external electroluminescence quantum efficiencies of up to 18.9% have been demonstrated by using these phthalonitrile and 2,3‐dicyanopyrazine‐based TADF emitters.