Energy Transfer Dynamics in Triplet–Triplet Annihilation Upconversion Using a Bichromophoric Heavy-Atom-Free Sensitizer,The Journal of Physical Chemistry A

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Energy Transfer Dynamics in Triplet–Triplet Annihilation Upconversion Using a Bichromophoric Heavy-Atom-Free Sensitizer
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2018-07-27 00:00:00 , DOI: 10.1021/acs.jpca.8b05901
Qi Chen ₁ , Yiming Liu ₁ , Xinyan Guo ₁ , Jiang Peng ₁ , Sofia Garakyaraghi ₂ , Christopher M. Papa ₂ , Felix N. Castellano ₂ , Dahui Zhao ₁ , Yuguo Ma ₁

Affiliation

A heavy-atom-free triplet sensitizer suitable for triplet–triplet annihilation-based photon upconversion was developed from the thermally activated delayed fluorescence (TADF) molecule 4CzPN by covalently tethering a pyrene derivative (DBP) as a triplet acceptor. The triplet exciton produced by 4CzPN is captured by the intramolecular pyrenyl acceptor and subsequently transferred via intermolecular triplet–triplet energy transfer (TTET) to freely diffusing pyrenyl acceptors in toluene. Transient absorption and time-resolved photoluminescence spectroscopy were employed to examine the dynamics of both the intra- and intermolecular TTET processes, and the results indicate that the intramolecular energy transfer from 4CzPN to DBP is swift, quantitative, and nearly irreversible. The reverse intersystem crossing is suppressed while intersystem crossing remains efficient, achieving high triplet yield and long triplet lifetime simultaneously. The ultralong excited state lifetime characteristic of the DBP triplet was shown to be crucial for enhancing the intermolecular TTET efficiency and the subsequent triplet–triplet annihilation photochemistry. It was also demonstrated that with the long triplet lifetime of the tethered DBP, TTET was enabled under low free acceptor concentrations and/or with sluggish molecular diffusion in polymer matrixes.

中文翻译：

三重态-三重态ni灭上转换中的能量转移动力学，使用双发色重无原子增感剂

通过共价束缚a衍生物（DBP）作为三重态受体，从热活化延迟荧光（TADF）分子4CzPN中开发了一种适用于基于三重态-三重态an灭的光子上转换的无重原子三重态敏化剂。由4CzPN产生的三重态激子被分子内的enyl基受体捕获，随后通过分子间的三重态-三重态能量转移（TTET）转移到free基受体在甲苯中的自由扩散。瞬态吸收和时间分辨光致发光光谱用于检查分子内和分子间TTET过程的动力学，结果表明从4CzPN到DBP的分子内能量转移是快速，定量和几乎不可逆的。反向系统间交叉得到抑制，而系统间交叉仍然有效，同时实现了较高的三重态产量和长的三重态寿命。DBP三重态的超长激发态寿命特征对于提高分子间TTET效率和随后的三重态-三重态an灭光化学至关重要。还证明了，通过拴系DBP的三重态寿命长，TTET在低游离受体浓度下和/或在聚合物基质中分子扩散缓慢的情况下成为可能。DBP三重态的超长激发态寿命特征对于提高分子间TTET效率和随后的三重态-三重态an灭光化学至关重要。还证明了，通过拴系DBP的三重态寿命长，TTET在低游离受体浓度下和/或在聚合物基质中分子扩散缓慢的情况下成为可能。DBP三重态的超长激发态寿命特征对于提高分子间TTET效率和随后的三重态-三重态an灭光化学至关重要。还证明了，通过拴系DBP的三重态寿命长，TTET在低游离受体浓度下和/或在聚合物基质中分子扩散缓慢的情况下成为可能。

更新日期：2018-07-27

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