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Yoon J, Kim SK, Kim HJ, Choi S, Jung SW, Lee H, Kim JY, Yoon DW, Han CW, Chae WS, Kwon JH, Cho MJ, Choi DH. Asymmetric Host Molecule Bearing Pyridine Core for Highly Efficient Blue Thermally Activated Delayed Fluorescence OLEDs. Chemistry 2020; 26:16383-16391. [PMID: 32686232 DOI: 10.1002/chem.202002655] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/16/2020] [Indexed: 01/12/2023]
Abstract
In this study, two host materials, pCzBzbCz and pCzPybCz, are synthesized to achieve a high efficiency and long lifetime of blue thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs). The molecular design strategy involves the introduction of a pyridine group into the core structure of pCzPybCz as an electron-withdrawing unit, and an electron-donating phenyl group into the structure of pCzBzbCz. These host materials demonstrate good thermal stability and high triplet energy (T1 =3.07 eV for pCzBzbCz and 3.06 eV for pCzPybCz) for the fabrication of blue TADF-OLEDs. In particular, pCzPybCz-based OLED devices demonstrate an external quantum efficiency (EQE) of 22.7 % and an operational lifetime of 24 h (LT90 , time to attain 90 % of initial luminance) at an initial luminance of 1000 cd m-2 . This superior lifetime could be explained by the C-N bond dissociation energy (BDE) in the host molecular structure. Furthermore, a mixed-host system using the electron-deficient 2,4-bis(dibenzo[b,d]furan-2-yl)-6-phenyl-1,3,5-triazine (DDBFT) is proposed to inhibit the formation of the anion state of our host materials. In short, the device operational lifetime is further improved by applying DDBFT. The carbazole-based asymmetric host molecule containing a pyridine core realizes a high-efficiency blue TADF-OLED showing a positive effect on the operating lifetime, and can provide useful strategies for designing new host materials.
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Affiliation(s)
- Jiwon Yoon
- Department of Chemistry, Research Institute for Natural Sciences, Institution Korea University, 145, Anam-ro, Sungbuk-gu, Seoul, 02841, Republic of Korea
| | - Seong Keun Kim
- Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - Hyung Jong Kim
- Department of Chemistry, Research Institute for Natural Sciences, Institution Korea University, 145, Anam-ro, Sungbuk-gu, Seoul, 02841, Republic of Korea
| | - Suna Choi
- Department of Chemistry, Research Institute for Natural Sciences, Institution Korea University, 145, Anam-ro, Sungbuk-gu, Seoul, 02841, Republic of Korea
| | - Sang Won Jung
- Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - Hyuna Lee
- Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - Jun Yun Kim
- LG Display, Co., Ltd., LG Science Park, 30, Magokjungang 10-ro, Gangseo-gu, Seoul, 07796, Republic of Korea
| | - Dae-Wi Yoon
- LG Display, Co., Ltd., LG Science Park, 30, Magokjungang 10-ro, Gangseo-gu, Seoul, 07796, Republic of Korea
| | - Chang Wook Han
- LG Display, Co., Ltd., LG Science Park, 30, Magokjungang 10-ro, Gangseo-gu, Seoul, 07796, Republic of Korea
| | - Weon-Sik Chae
- Daegu Center, Korea Basic Science Institute, 80 Daehakro, Bukgu, Daegu, 41566, Republic of Korea
| | - Jang Hyuk Kwon
- Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - Min Ju Cho
- Department of Chemistry, Research Institute for Natural Sciences, Institution Korea University, 145, Anam-ro, Sungbuk-gu, Seoul, 02841, Republic of Korea
| | - Dong Hoon Choi
- Department of Chemistry, Research Institute for Natural Sciences, Institution Korea University, 145, Anam-ro, Sungbuk-gu, Seoul, 02841, Republic of Korea
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