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Stabilization of Blue Emitters with Thermally Activated Delayed Fluorescence by the Steric Effect: A Case Study by means of Magnetic Field Effects
Physical Review Applied ( IF 4.6 ) Pub Date : 2020-09-23 , DOI: 10.1103/physrevapplied.14.034059 Chongguang Zhao , Fenggui Zhao , Kai Wang , Haomiao Yu , Tianyu Huang , Rui Wang , Caixia Zhang , Bin Hu , Lian Duan
Physical Review Applied ( IF 4.6 ) Pub Date : 2020-09-23 , DOI: 10.1103/physrevapplied.14.034059 Chongguang Zhao , Fenggui Zhao , Kai Wang , Haomiao Yu , Tianyu Huang , Rui Wang , Caixia Zhang , Bin Hu , Lian Duan
The use of steric hindrance in blue thermally activated delayed fluorophores shows empirically the improvement of operational lifetime for organic light-emitting diodes (OLEDs). Nevertheless, the intrinsic mechanism of this strategy remains unclear and elusive. Here, the steric effects on rate coefficient and degradation probability of bimolecular quenching processes are decoupled by magnetic field effects and quantum-chemical calculation. The respective dependence of magnetoelectroluminescence on triplet density and charge-carrier density indicates that triplet-charge quenching (TCQ) is the dominant degradation mechanism over that of triplet-triplet annihilation, where steric hindrance effectively prevents the occurrence of Dexter-type TCQ and significantly reduces the TCQ rate coefficient. On the contrary, only a slight increase in degradation probability is generated by the steric effect from bulk inert groups. These findings will provide unambiguous guidance for the design of functional materials for OLEDs.
中文翻译:
立体效应稳定热激活延迟荧光的蓝色发射体:以磁场效应为例
在蓝色热激活延迟荧光团中使用空间位阻在经验上显示出有机发光二极管(OLED)的使用寿命的提高。但是,该策略的内在机制仍不清楚和难以捉摸。在这里,空间效应对速率系数和双分子淬灭过程的降解概率的影响是通过磁场效应和量子化学计算来分离的。磁电致发光对三重态密度和电荷载流子密度的依赖性表明,三重态电荷猝灭(TCQ)是三重态-三重态an灭的主要降解机理,其中空间位阻有效地防止了Dexter型TCQ的发生并显着降低了TCQ速率系数。反之,整体惰性基团的空间效应只会使降解几率略有增加。这些发现将为OLED的功能材料设计提供明确的指导。
更新日期:2020-09-23
中文翻译:
立体效应稳定热激活延迟荧光的蓝色发射体:以磁场效应为例
在蓝色热激活延迟荧光团中使用空间位阻在经验上显示出有机发光二极管(OLED)的使用寿命的提高。但是,该策略的内在机制仍不清楚和难以捉摸。在这里,空间效应对速率系数和双分子淬灭过程的降解概率的影响是通过磁场效应和量子化学计算来分离的。磁电致发光对三重态密度和电荷载流子密度的依赖性表明,三重态电荷猝灭(TCQ)是三重态-三重态an灭的主要降解机理,其中空间位阻有效地防止了Dexter型TCQ的发生并显着降低了TCQ速率系数。反之,整体惰性基团的空间效应只会使降解几率略有增加。这些发现将为OLED的功能材料设计提供明确的指导。