|
|
|
| Molecular engineering on all ortho-linked carbazole/oxadiazole hybrids toward highly-efficient thermally activated delayed fluorescence materials in OLEDs |
| Wenbo Yuana, Hannan Yangb, Mucan Zhanga, Die Hua, Shigang Wana, Zijing Lia, Changsheng Shib, Ning Sunb, Youtian Taoa, Wei Huanga,c |
a Key Lab for Flexible Electronics & Institute of Advanced Materials(IAM), Nanjing Tech University, Nanjing 211816, China;
b Department of Physics, Center for Optoelectronics Engineering Research, Yunnan University, Kunming 650091, China;
c Shaanxi Institute of Flexible Electronics(SIFE), North western Polytechnical University(NPU), Xi'an 710072, China |
|
|
|
| Guide All ortho-linked D-A and D-A-D molecules exhibit non-TADF feature due to broad spatial overlap at triplet excited state for large △EST,while A-D-A compounds show strong TADF property owing to efficient spatial separation for small △EST. |
|
|
Abstract The highest efficiency thermally activated delayed fluorescence (TADF) emitters in OLEDs are mostly based on twisted donor/acceptor (D/A) type organic molecules. Herein, we report the rational molecular design on twisted all ortho-linked carbazole/oxadiazole (Cz/OXD) hybrids with tunable D-A interactions by adjusting the numbers of donor/acceptor units and electron-donating abilities. Singlet-triplet energy bandgaps (ΔEST) are facilely tuned from~0.4, 0.15 to~0 eV in D-A, D-A-D to A-D-A type compounds. This variation correlates well with triplet-excited-state frontier orbital spatial separation efficiency. NonTADF feature with solid state photoluminescence quantum yield (PLQY)<10% is observed in D-A type 2CzOXD and D-A-D type 4CzOXD. Owing to the extremely low ΔEST for efficient reverse intersystem crossing, strong TADF with PLQY of 71%-92% is achieved in A-D-A type 4CzDOXD and 4tCzDOXD. High external quantum efficiency from 19.4% to 22.6% is achieved in A-D-A typed 4CzDOXD and 4tCzDOXD.
|
|
Received: 27 June 2019
|
| Fund: We thank the National Natural Science Foundation of China (Nos. 91833304, 61805211), National Key Research and Development Program of China for the Joint Research Program between China and European Union (No. 2016YFE0112000), the Natural Science Foundation of Jiangsu Province (Nos. BK20160042 and XYDXX-026) and the Foundation for the Author of National Excellent Doctoral Dissertation of China FANEDD (No. 201436). |
|
Corresponding Authors:
Changsheng Shi, Youtian Tao
E-mail: csshi@ynu.edu.cn;iamyttao@njtech.edu.cn
|
|
|
|
| [1] |
C.W. Tang, S.A. VanSlyke, Appl. Phys. Lett. 51(1987) 913-915.
|
| [2] |
Y. Ma, H. Zhang, J. Shen, C. Che, Synth. Met. 94(1998) 245-248.
|
| [3] |
S. Gong, Y. Chen, C. Yang, et al., Adv. Mater. 22(2010) 5370-5373.
|
| [4] |
M.A. Baldo, D.F. O'Brien, Phys. Rev. B 60(1999) 14422-14428.
|
| [5] |
F. Wang, Y. Tao, W. Huang, Acta Chim. Sin. 73(2015) 9-22.
|
| [6] |
H. Uoyama, K. Goushi, K. Shizu, H. Nomura, C. Adachi, Nature 492(2012) 234-238.
|
| [7] |
X. Cao, D. Zhang, S. Zhang, Y. Tao, W. Huang, J. Mater. Chem. C 5(2017) 7699-7714.
|
| [8] |
Z. Yang, Z. Mao, Z. Xie, et al., Chem. Soc. Rev. 46(2017) 915-1016.
|
| [9] |
M.Y. Wong, E.Z. Colman, Adv. Mater. 29(2017) 1605444.
|
| [10] |
L.Y. Zhao, Y.N. Liu, S.F. Wang, et al., Chin. J. Polym. Sci. 35(2017) 490-502.
|
| [11] |
H. Wang, X. Lv, L. Meng, et al., Chin. Chem. Lett. 29(2018) 471-474.
|
| [12] |
X. Tian, H. Sun, Q. Zhang, C. Adachi, Chin. Chem. Lett. 27(2016) 1445-1452.
|
| [13] |
B. Frederichs, H. Staerk, Chem. Phys. Lett. 460(2008) 116-118.
|
| [14] |
H. Tanaka, K. Shizu, H. Nakanotani, C. Adachi, Chem. Mater. 25(2013) 3766-3771.
|
| [15] |
D.R. Lee, B.S. Kim, C.W. Lee, et al., ACS Appl. Mater. Interfaces 7(2015) 9625-9629.
|
| [16] |
T. Huang, W. Jiang, L. Duan, J. Mater. Chem. C 6(2018) 5577-5596.
|
| [17] |
Y. Liu, C. Li, Z. Ren, S. Yan, M.R. Bryce, Nat. Rev. Mater. 3(2018) 18020.
|
| [18] |
J.X. Chen, K. Wang, C.J. Zheng, et al., Adv. Sci. 5(2018) 1800436.
|
| [19] |
W. Zeng, H.Y. Lai, W.K. Lee, et al., Adv. Mater. 30(2018) 1704961.
|
| [20] |
T.A. Lin, T. Chatterjee, W.L. Tsai, et al., Adv. Mater. 28(2016) 6976-6983.
|
| [21] |
M. Taneda, K. Shizu, H. Tanaka, C. Adachi, Chem. Commun. 51(2015) 5028-5031.
|
| [22] |
T.L. Wu, M.J. Huang, C.C. Lin, et al., Nat. Photonics 12(2018) 235-240.
|
| [23] |
Y.T. Lee, P.C. Tseng, T. Komino, et al., ACS Appl. Mater. Interface 10(2018) 43842-43849.
|
| [24] |
P.L.D. Santos, J.S. Ward, D.G. Congrave, et al., Adv. Sci. 5(2018) 1700989.
|
| [25] |
C. Tang, T. Yang, X. Cao, et al., Adv. Opt. Mater. 3(2015) 786-790.
|
| [26] |
X. Yang, D.C. Müller, D. Neher, K. Meerholz, Adv. Mater. 18(2006) 948-954.
|
| [27] |
N. Rehmann, C. Ulbricht, A. Köhnen, et al., Adv. Mater. 20(2008) 129-133.
|
| [28] |
Y. Tao, Q. Wang, C. Yang, et al., Angew. Chem. Int. Ed. 47(2008) 8104-8107.
|
| [29] |
Y. Tao, Q. Wang, C. Yang, et al., Adv. Funct. Mater. 20(2010) 304-311.
|
| [30] |
Y. Tao, C. Yang, J. Qin, Chem. Soc. Rev. 40(2011) 2943-2970.
|
| [31] |
M.W. Cooper, X. Zhang, Y. Zhang, et al., Chem. Mater. 30(2018) 6389-6399.
|
| [32] |
X. Zhang, M.W. Cooper, Y. Zhang, et al., ACS Appl. Mater. Interfaces 11(2019) 12693-12698.
|
| [33] |
D. Zhou, D. Liu, X. Gong, et al., ACS Appl. Mater. Interfaces 11(2019) 24339-24348.
|
| [34] |
F. Wang, X. Cao, L. Mei, et al., Chin. J. Chem. 36(2018) 241-246.
|
| [35] |
D. Zhang, X. Cao, Q. Wu, et al., J. Mater. Chem. C 6(2018) 3675-3682.
|
| [36] |
K. Goushi, K. Yoshida, K. Sato, C. Adachi, Nat. Photonics 6(2012) 253-258.
|
|
|
|
