Mechanism of the Triplet-to-Singlet Upconversion in the Assistant Dopant ACRXTN
Mechanism of the Triplet-to-Singlet Upconversion in the Assistant Dopant ACRXTN
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DOI：
10.1021/acs.jpcc.6b00060
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发表时间：
2016-02-25
影响因子：
3.7
通讯作者：
Marian, Christel M.
中科院分区：
文献类型：
--
作者：
Marian, Christel M.
本文采用密度泛函理论和多参考构型相互作用量子化学方法研究了3-（9，9-二甲基吖啶-10（9 H）-基）-9H-咕吨-9-酮（ACRXTN）的分子动力学性质。ACRXTN最近被用作绿色发光有机发光二极管（OLED）中的辅助掺杂剂，显著提高了OLED的外部电致发光量子效率。在ARCXTN实验中发现的有效的三重态到单重态的上转换不能仅仅基于小的单重态-三重态能隙来解释。我们发现五个相互作用的电子激发态在一个小的能量间隔：从吖啶的氧杂蒽酮的电荷转移激发（三重态和单重态），本地氧杂蒽酮三重态（π π *）激发，和一对三重态和单重态起源于氧杂蒽酮上的n π * 激发。在计算的自旋轨道耦合常数和势能分布的基础上，我们提出三重态（pi pi*）介导了ACRXTN中三重态到单重态的上转换，并且羰基键伸展运动在这个过程中起着至关重要的作用。
In this work, the photophysics of 3-(9,9-dimethylacridin-10(9H)-yl)-9H-xanthen-9-one (ACRXTN) has been investigated by combined density functional theory and multireference configuration interaction quantum chemical methods. ACRXTN was recently utilized as an assistant dopant in a green emitting organic light-emitting diode (OLED), increasing substantially the external electroluminescence quantum efficiency of the OLED. The efficient triplet-to-singlet upconversion, found experimentally in ARCXTN, cannot be explained solely on the basis of a small singlet-triplet energy gap. We find five interacting electronically excited states in a small energy interval: a charge-transfer excitation (triplet and singlet) from acridine to xanthone, a local xanthone triplet (pi pi*) excitation, and a pair of triplet and singlet states originating from an n pi* excitation on xanthone. On the basis of calculated spin orbit coupling constants and potential energy profiles, we propose here that the triplet (pi pi*) state mediates the triplet-to-singlet upconversion in ACRXTN and that the carbonyl bond stretching motion plays an essential role in this process.