Yoon Sung Joon, Kim Ji Han, Chung Won Jae, Lee Jun Yeob
School of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do, 440-746, Republic of Korea.
Chemistry. 2021 Feb 10;27(9):3065-3073. doi: 10.1002/chem.202004042. Epub 2021 Jan 14.
In this work, a design approach of three thermally activated delayed fluorescence (TADF) emitters to extend the device lifetime of the TADF sensitized fluorescent devices was studied. Three TADF materials, 5-{4,6-bis[4-(tert-butyl)phenyl]-1,3,5-triazin-2-yl}-2-(10,15-diphenyl-10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazol-5-yl)benzonitrile (tTCNTruX), 4-[3-cyano-4-(10,15-diphenyl-10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazol-5-yl)phenyl]-2,6-diphenylpyrimidine-5-carbonitrile (PCNTruX) and 4-(4-{10,15-bis[4-(tert-butyl)phenyl]-10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazol-5-yl}-3-cyanophenyl)-2,6-diphenylpyrimidine-5-carbonitrile (PCNtTruX), were synthesized as sensitizers for TADF-sensitized fluorescent organic light-emitting diodes. The two tTCNTruX and PCNtTruX TADF emitters were designed to have Dexter energy transfer with blocking groups either in the donor or acceptor unit of the donor-acceptor-type TADF sensitizer. The TADF materials showed small singlet-triplet energy splitting and a high reverse intersystem crossing (RISC) rate for effective sensitization of the fluorescent emission of the fluorescent emitter. tTCNTruX- and PCNtTruX-sensitized fluorescent devices showed maximum external quantum efficiencies (EQEs) of 17.7 % and 11.5 % in the yellow and red devices, respectively, which were higher than those of TADF-sensitized devices with the corresponding TADF sensitizer without a blocking group. Moreover, the device lifetime was also extended by employing the tTCNTruX and PCNtTruX sensitizers. This work demonstrated that the tTCNTruX and PCNtTruX sensitizers are effective to improve the maximum EQE and device lifetime of TADF-sensitized fluorescent devices.
在这项工作中，研究了三种热激活延迟荧光（TADF）发光体的设计方法，以延长TADF敏化荧光器件的器件寿命。合成了三种TADF材料，5-{4,6-双[4-(叔丁基)苯基]-1,3,5-三嗪-2-基}-2-(10,15-二苯基-10,15-二氢-5H-二吲哚并[3,2-a:3',2'-c]咔唑-5-基)苯甲腈（tTCNTruX）、4-[3-氰基-4-(10,15-二苯基-10,15-二氢-5H-二吲哚并[3,2-a:3',2'-c]咔唑-5-基)苯基]-2,6-二苯基嘧啶-5-腈（PCNTruX）和4-(4-{10,15-双[4-(叔丁基)苯基]-10,15-二氢-5H-二吲哚并[3,2-a:3',2'-c]咔唑-5-基}-3-氰基苯基)-2,6-二苯基嘧啶-5-腈（PCNtTruX），作为TADF敏化荧光有机发光二极管的敏化剂。两种tTCNTruX和PCNtTruX TADF发光体被设计为在供体-受体型TADF敏化剂的供体或受体单元中带有阻断基团的德克斯特能量转移。这些TADF材料显示出较小的单重态-三重态能量分裂和较高的反向系间窜越（RISC）速率，以有效地敏化荧光发射体的荧光发射。tTCNTruX和PCNtTruX敏化的荧光器件在黄色和红色器件中分别显示出17.7%和11.5%的最大外量子效率（EQE），高于使用相应无阻断基团的TADF敏化剂的TADF敏化器件。此外，通过使用tTCNTruX和PCNtTruX敏化剂，器件寿命也得到了延长。这项工作表明，tTCNTruX和PCNtTruX敏化剂对于提高TADF敏化荧光器件的最大EQE和器件寿命是有效的。
