Chromenopyrazole-Based Bipolar Blue Host Materials for Highly Efficient Thermally Activated Delayed Fluorescence Organic Light Emitting Diodes
- Authors
- Godumala, Mallesham; Choi, Suna; Park, Seo Yeon; Cho, Min Ju; Kim, Hyung Jong; Ahn, Dae Hyun; Moon, Ji Su; Kwon, Jang Hyuk; Choi, Dong Hoon
- Issue Date
- 14-8월-2018
- Publisher
- AMER CHEMICAL SOC
- Citation
- CHEMISTRY OF MATERIALS, v.30, no.15, pp.5005 - 5012
- Indexed
- SCIE
SCOPUS
- Journal Title
- CHEMISTRY OF MATERIALS
- Volume
- 30
- Number
- 15
- Start Page
- 5005
- End Page
- 5012
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/73769
- DOI
- 10.1021/acs.chemmater.8b01207
- ISSN
- 0897-4756
- 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 (similar to 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.
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