Effect of Vibronic Coupling on Correlated Triplet Pair Formation in the Singlet Fission Process of Linked Tetracene Dimers
Effect of Vibronic Coupling on Correlated Triplet Pair Formation in the Singlet Fission Process of Linked Tetracene Dimers
复制标题
电子振动耦合对连接并四苯二聚体单线态裂变过程中相关三线态对形成的影响
DOI：
10.1021/acs.jpca.0c03041
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Hironori Kaji
中科院分区：
文献类型：
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作者：
Katsuyuki Shizu;Chihaya Adachi;Hironori Kaji
基于四烯的单重态裂变（SF）材料作为三重态敏化剂在有机光电子学中显示出很好的应用前景。SF涉及从光激发单重态1（S1 S 0）到相关三重态对1（T1 T1）的内部转换。我们推导出一个表达式的基础上的费米黄金法则与人工洛伦兹加宽的内部转换率。内转换率取决于态间电子振动耦合（VC）和1（S1 S 0）和1（T1 T1）之间的能量差（ΔESF）。因此，了解状态间VC和Δ ESF之间的相互作用对于揭示结构-性质关系如何影响SF效率是必要的。在这里，我们提出了一种方法来定量分析1（S1 S 0）和1（T1 T1）之间的州际VC。我们将这种方法应用于SF inortho-，Meta-，和para-bis（ethynyltetracenyl）benzene，并确定了1（T1 T1）形成速率的州际VC的效果。中间二聚体的状态间VC非常弱，这合理地解释了实验获得的慢1（T1 T1）形成速率。弱VC是由于间二聚体的1（S1 S 0）和1（T1 T1）之间的重叠密度非常小。进一步研究了对映体1（T1 T1）生成速率的结构依赖性，发现当并四苯单元间的旋转角较大时，对映体1（T1 T1）生成速率比邻位和间位二聚体快，且具有较大的VC和较小的Δ ESF.并四苯单元的旋转是实验观察到的快速1（T1 T1）形成速率的paradimer的起源。
Tetracene-based singlet fission (SF) materials show application prospects as triplet sensitizers in organic optoelectronics. SF involves internal conversion from photoexcited singlet states1(S1S0) to correlated triplet pair states1(T1T1). We derive an expression for the internal conversion rate on the basis of the Fermi golden rule with an artificial Lorentzian broadening. The internal conversion rate depends on the interstate vibronic couplings (VCs) and energy difference (ΔESF) between1(S1S0) and1(T1T1). Therefore, understanding the interplay between interstate VCs and ΔESFis necessary to reveal how the structure–property relationship affects the SF efficiency. Here, we propose a method to quantitatively analyze interstate VCs between1(S1S0) and1(T1T1). We apply this method to SF inortho-,meta-, andpara-bis(ethynyltetracenyl)benzene and identify an effect of interstate VCs on the1(T1T1) formation rate. The interstate VCs of themetadimer are remarkably weak, which reasonably explains the experimentally obtained slow1(T1T1) formation rate. The weak VCs result from a very small overlap density between1(S1S0) and1(T1T1) of themetadimer. Furthermore, we investigate structure-dependence of the1(T1T1) formation rate of theparadimer and find that theparadimer shows large VCs and small ΔESFwhen the rotational angle between the two tetracene units is large, which leads to the faster1(T1T1) formation rate than those of theorthoandmetadimers. The rotation of the tetracene units is the origin of the experimentally observed fast1(T1T1) formation rate of theparadimer.