Abstract
New electron-acceptor cores are necessary for developing highly efficient bipolar hosts, particularly for blue thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs). Herein, chromenopyrazole (CP) was used for the first time as an electron-acceptor core to design and synthesize two novel blue bipolar hosts, viz., 8-(9H-carbazol-9-yl)-3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-one (CzCP) and 8-(9H-[3,9′-bicarbazol]-9-yl)-3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-one (2CzCP). The influence of donor strength on the photophysical, electrochemical, and electroluminescent performances was systematically investigated. CzCP and 2CzCP both maintain high triplet energy (∼3.0 eV), appropriate highest occupied and lowest unoccupied energy levels (HOMO/LUMO), and bipolar nature. Consequently, OLEDs containing CzCP as a host in the emissive layer exhibited state-of-the-art performance with external quantum efficiency of 27.9% and CIE color coordinates of (0.15, 0.21), thus achieving excellent performance among all reported blue host materials in TADF-OLEDs. This work highlights the importance of the CP unit in developing new host materials and paves the way for the realization of high-efficiency blue TADF-OLEDs.
Original language | English |
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Pages (from-to) | 5005-5012 |
Number of pages | 8 |
Journal | Chemistry of Materials |
Volume | 30 |
Issue number | 15 |
DOIs | |
Publication status | Published - 2018 Aug 14 |
Bibliographical note
Funding Information:This work was supported by the National Research Foundation of Korea (NRF2015R1A2A1A05001876) and by the Key Research Institute Program (NRF20100020209). D. H. Choi particularly thanks for the support from LG display Co. Limited (2017−2018). It was also supported by a Korea University Grant (2017-2018).
Publisher Copyright:
© 2018 American Chemical Society.
ASJC Scopus subject areas
- General Chemistry
- General Chemical Engineering
- Materials Chemistry