A quantum dynamics study of the hyperfluorescence mechanism
A quantum dynamics study of the hyperfluorescence mechanism
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DOI：
10.1039/d0tc04225k
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发表时间：
2021-01-28
影响因子：
6.4
通讯作者：
Penfold, Thomas
中科院分区：
文献类型：
--
作者：
Giret, Yvelin;Eng, Julien;Penfold, Thomas
利用热激活延迟荧光（TADF）结合有效的福斯特共振能量转移（FRET）到狭窄的荧光发射器的三重态收获被视为一种有前途的方法，以实现有机发光二极管（oled）的高效率和颜色纯度。在这项工作中，我们进行了量子化学和量子动力学模拟，以模拟具有Au桥接金属（Au- cz）的碳金属酰胺（CMA）分子和窄蓝色荧光发射体2,5,8,11-四叔丁基苝（TBPe）之间的所谓高荧光（HF）过程。我们的量子动力学模拟表明，FRET速率类似于10(10)s(-1)，表明它发生在皮秒时间尺度上，与Au-Cz的ISC交叉速率相当。这种高FRET率，这是最强烈地依赖于供体和受体分子的S-1状态之间的能量差，是有利的设备，因为它鼓励快速三重态收获。此外，与大多数有机体系相比，可比较的FRET和系统间交叉（ISC）速率将有助于利用光激发研究这一机制。除了FRET速率外，还从量子动力学模拟中估计了供体和受体分子之间不同能量差的福斯特半径，并与不同系统的实验估计在定量上一致，表明量子核动力学模拟可以成为增强我们对高荧光基发射器理解的重要工具。
Triplet state harvesting using thermally-activated delayed fluorescence (TADF) combined with efficient Forster resonant energy transfer (FRET) to a narrow fluorescent emitter is seen as a promising approach to achieve high efficiency and colour-purity in organic light-emitting diodes (OLEDs). In this work, we perform quantum chemistry and quantum dynamics simulations to model the so-called hyperfluorescence (HF) process between a carbene-metal-amide (CMA) molecule with a Au bridging metal (Au-Cz) and a narrow blue fluorescent emitter, 2,5,8,11-tetra-tert-butylperylene (TBPe). Our quantum dynamics simulations illustrate a FRET rate of similar to 10(10) s(-1) indicating that it occurs on the picosecond timescale comparable with the ISC crossing rate of Au-Cz. This high FRET rate, which is most strongly dependent on the energy difference between the S-1 states of the donor and acceptor molecules, is advantageous for devices as it encourages rapid triplet harvesting. In addition, the comparable FRET and intersystem crossing (ISC) rates, in contrast to most organic only systems, would facilitate studying this mechanism using photoexcitation. Besides the FRET rate, Forster radii are also estimated from the quantum dynamics simulations for different energy differences between the donor and acceptor molecules and are in quantitative agreement with the experimental estimations for different systems, showing that quantum nuclear dynamics simulation could be an important tool for enhancing our understanding of hyperfluorescence-based emitters.