Efficiency Breakthrough of Fluorescence OLEDs by the Strategic Management of "Hot Excitons" at Highly Lying Excitation Triplet Energy Levels
Efficiency Breakthrough of Fluorescence OLEDs by the Strategic Management of "Hot Excitons" at Highly Lying Excitation Triplet Energy Levels
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DOI：
10.1002/adfm.202106912
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发表时间：
2021-09-02
影响因子：
19
通讯作者：
Ma, Dongge
中科院分区：
文献类型：
--
作者：
Lin, Chengwei;Han, Pengbo;Ma, Dongge
聚集诱导发射（AIE）和杂化局部和电荷转移（HLCT）材料是两种很有前途的电致发光系统，用于利用高三重态激子（T-n, n >= 2）的“热激子”来制造高效有机发光二极管（oled）。然而，由于可能损失T-n -> Tn-1，所得oled的效率没有达到预期。在此,实验结果和理论计算证明高山之间的“热激子”过程三重态条t - 3和单重态的最低激发态AIE材料4 s - 1“- (diphenylamino) 2”,5”二苯基-[1,1”:4 ' 1 ":4 ",1“:4“,”“-quinquephenyl] 4-carbonitrile (TPB-PAPC)和发现福斯特共振能量转移(FRET)两个分子之间可以促进“热激子”过程和抑制条t - 3 - > 2损失通过掺杂蓝色TPB-PAPC荧光发射器。最后，掺杂的TPB-PAPC蓝色oled实现了9.0%的最大外量子效率（EQE(max)），效率滚降很小。在HLCT材料2-（4-（10-（3-（9h -咔唑-9-基）苯基）蒽-9-基）苯基）-1-苯基- 1h -菲蒽[9,10-d]咪唑（PAC）中掺杂蓝色荧光发射器作为发射层，得到的蓝色oled的EQE（max）为17.4%，实现了蓝色荧光oled效率的突破。这项工作建立了高性能“热激子”分子设计和高性能蓝色荧光oled制造的物理见解。
Aggregation-induced emission (AIE) and hybridized local and charge-transfer (HLCT) materials are two kinds of promising electroluminescence systems for the fabrication of high-efficiency organic light-emitting diodes (OLEDs) by harnessing "hot excitons" at the high-lying triplet exciton states (T-n, n >= 2). Nonetheless, the efficiency of the resulting OLEDs did not meet expectations due to the possible loss of T-n -> Tn-1. Herein, experimental results and theoretical calculations demonstrate the "hot exciton" process between the high-lying triplet state T-3 and the lowest excited singlet state S-1 in an AIE material 4 ''''-(diphenylamino)-2 '',5 ''-diphenyl-[1,1 '':4 ',1 '':4 '',1 ''':4 ''',1 ''''-quinquephenyl]-4-carbonitrile (TPB-PAPC) and it is found that the Forster resonance energy transfer (FRET) between two molecules can facilitate the "hot exciton" process and inhibit the T-3 -> T-2 loss by doping a blue fluorescent emitter in TPB-PAPC. Finally, the doped TPB-PAPC blue OLEDs achieve a maximum external quantum efficiency (EQE(max)) of 9.0% with a small efficiency roll-off. Furthermore, doping the blue fluorescent emitter in a HLCT material 2-(4-(10-(3-(9H-carbazol-9-yl)phenyl)anthracen-9-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d] imidazole (PAC) is used as the emission layer, and the resulting blue OLEDs exhibit an EQE(max) of 17.4%, realizing the efficiency breakthrough of blue fluorescence OLEDs. This work establishes a physical insight in the design of high-performance "hot exciton" molecules and the fabrication of high-performance blue fluorescence OLEDs.