Deep‐Red/Near‐Infrared Delayed Fluorescence Luminophores Based on DipyridoPhenazine‐11,12‐Dicarbonitrile for High‐Performance OLEDs

• Published in: Advanced optical materials 2023-07, Vol.11 (14)
• Main Authors: Cai, Zheyi, Liu, Zhangshan, Wu, Xing, Guo, Jingjing, Ben Zhong Tang, Zhao, Zujin
• Format: Article
• Language: English
• Subjects: Dipoles; Doped films; Fluorescence; Materials science; Near infrared radiation; Optics; Organic light emitting diodes; Organic materials; Photoluminescence; Quantum efficiency
• ISSN: 2195-1071
• DOI: 10.1002/adom.202300404

Deep‐red (DR) and near‐infrared (NIR) organic light‐emitting diodes (OLEDs) based on purely organic materials hold great potential in various frontier applications, but purely organic DR/NIR materials are far from satisfactory. Herein, a series of tailor‐made delayed fluorescence luminophores comprised of electron‐withdrawing dipyrido[3,2‐a:2″,3″‐c]phenazine‐11,12‐dicarbonitrile and various electron‐donating triarylamines are developed, and their thermal and electrochemical stabilities, electronic structures, photophysical properties and electroluminescence (EL) performances are investigated. They exhibit strong NIR emissions (758−767 nm) in neat films and DR/NIR emissions (680−691 nm) with good photoluminescence quantum yields (48−60%) in doped films, and prefer ordered horizontal alignment with high horizontal dipole ratios of 82−90%, which are attributed to the hybrid transition components of excited states, extended molecular plane and intramolecular hydrogen‐bonding. Their non‐doped OLEDs emit purely NIR light peaking at 820−834 nm with maximum external quantum efficiencies (ηext,maxs) of 0.66−1.06%, and thier doped OLEDs radiate DR/NIR emissions peaking at 656−748 nm with superb ηext,maxs of 14.4–31.0%. They present even better EL performances in sensitized OLEDs, with DR emissions peaking at 648−656 nm and higher ηext,maxs of 29.7−32.9%. These state‐of‐the‐art EL performances demonstrate the great potential of the developed DR/NIR delayed fluorescence luminophores in practical application.