Spin Statistics for Triplet-Triplet Annihilation Upconversion: Exchange Coupling, Intermolecular Orientation, and Reverse Intersystem Crossing.
Spin Statistics for Triplet-Triplet Annihilation Upconversion: Exchange Coupling, Intermolecular Orientation, and Reverse Intersystem Crossing.
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三重态-三重态湮灭上转换的自旋统计：交换耦合，分子间取向和反向系间交叉。
DOI：
10.1021/jacsau.1c00322
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发表时间：
2021-12-27
期刊：
影响因子：
8
通讯作者：
Clark J
中科院分区：
文献类型：
--
作者：
Bossanyi DG;Sasaki Y;Wang S;Chekulaev D;Kimizuka N;Yanai N;Clark J
三重态-三重态湮灭上转换(TTA-UC)具有显著提高光伏电池的光捕获能力的巨大潜力，也是生物医学领域的研究热点。影响TTA-UC整体效率的因素很多，其中最基本的是自旋统计因子η，它给出了由一对湮灭三重态形成明亮单线态的概率。在确定η对有机发光二极管整体效率的贡献时，TTA的值也是至关重要的。以固体Rubrene为模型系统，我们重申了为什么实验测量的磁场效应证明湮灭三重态首先形成弱交换耦合的三重态。这与传统的TTA-UC隐含假设强交换耦合的讨论相反，我们证明了它对自旋统计因子η有着深远的影响。例如，分子间取向的变化将η从三重态对波函数的自旋混合调整为自旋混合。由于自旋-1三重态的命运对决定η特别重要，我们利用泵浦-推-探测光谱在Rubrene中研究了它，并为最近报道的高能级反向系间交叉通道找到了额外的证据。我们将所有这些因素纳入到一个更新的模型框架中，用它来理解TTA-UC的自旋统计，并用它来合理解释不同常见湮没系统之间报告的η值的差异。我们认为，在新的零化子分子中利用高水平的反向系间交叉通道可能是一个非常有希望的超过任何自旋统计极限的策略。
Triplet–triplet annihilation upconversion (TTA-UC) has great potential to significantly improve the light harvesting capabilities of photovoltaic cells and is also sought after for biomedical applications. Many factors combine to influence the overall efficiency of TTA-UC, the most fundamental of which is the spin statistical factor, η, that gives the probability that a bright singlet state is formed from a pair of annihilating triplet states. The value of η is also critical in determining the contribution of TTA to the overall efficiency of organic light-emitting diodes. Using solid rubrene as a model system, we reiterate why experimentally measured magnetic field effects prove that annihilating triplets first form weakly exchange-coupled triplet-pair states. This is contrary to conventional discussions of TTA-UC that implicitly assume strong exchange coupling, and we show that it has profound implications for the spin statistical factor η. For example, variations in intermolecular orientation tune η from to through spin mixing of the triplet-pair wave functions. Because the fate of spin-1 triplet-pair states is particularly crucial in determining η, we investigate it in rubrene using pump–push–probe spectroscopy and find additional evidence for the recently reported high-level reverse intersystem crossing channel. We incorporate all of these factors into an updated model framework with which to understand the spin statistics of TTA-UC and use it to rationalize the differences in reported values of η among different common annihilator systems. We suggest that harnessing high-level reverse intersystem crossing channels in new annihilator molecules may be a highly promising strategy to exceed any spin statistical limit.
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影响因子：
16.6
作者：
Basel BS;Zirzlmeier J;Hetzer C;Phelan BT;Krzyaniak MD;Reddy SR;Coto PB;Horwitz NE;Young RM;White FJ;Hampel F;Clark T;Thoss M;Tykwinski RR;Wasielewski MR;Guldi DM
通讯作者：
Guldi DM
影响因子：
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作者：
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作者：
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通讯作者：
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作者：
ATKINS, PW;EVANS, GT
通讯作者：
EVANS, GT
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8.6
作者：
Bayliss, Sam L.;Chepelianskii, Alexei D.;Greenham, Neil C.
通讯作者：
Greenham, Neil C.