Role of Intermolecular Interactions in the Excited-State Photophysics of Tetracene and 2,2′-Ditetracene,The Journal of Physical Chemistry C

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Role of Intermolecular Interactions in the Excited-State Photophysics of Tetracene and 2,2′-Ditetracene
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-08-11 , DOI: 10.1021/acs.jpcc.0c04066
Ulrich Müller ₁ , Lena Roos ₂ , Maximilian Frank ₁ , Marian Deutsch ₃ , Sebastian Hammer ₁ , Marcel Krumrein ₁ , Alexandra Friedrich ₄ , Todd B. Marder ₄ , Bernd Engels ₃ , Anke Krueger _{2,

5} , Jens Pflaum _{1,

6}

Affiliation

We carried out a comparative study on the excited-state properties of tetracene, which is prone to singlet fission, and its 2,2′-ditetracene derivative to analyze the dependence of such loss channels on molecular packing and, thus, intermolecular interactions. In neat single crystals, the absorption and emission spectra of 2,2′-ditetracene are significantly red-shifted by about 150 meV from those of tetracene, while in the case of isolated molecules dispersed in crystalline anthracene matrixes, both dyes show virtually identical emission patterns. Unlike tetracene, the absence of delayed fluorescence in 2,2′-ditetracene single-crystal photoluminescence (PL) and time-dependent density functional theory (DFT) calculations based on experimental single-crystal structures indicate a decline in the excited singlet-state energy below the E(S₁) = 2E(T₁) threshold. Simultaneously, time-resolved temperature-dependent PL data reveal an interplay of the molecular S₁ state and an excited dimer state, which is efficiently populated above 10 K. Upon cooling, the photoluminescence of 2,2′-ditetracene crystals outperforms that of tetracene by more than an order of magnitude and highlights the potential of molecular design, here the covalent linking of two tetracenes, to conserve the optical properties of the individual chromophores while decisively improving their photophysical properties in the crystalline aggregate.

中文翻译：

分子间相互作用在四足额和2,2'-双足示踪物激发态光物理中的作用

我们对易于发生单重态裂变的并四苯及其2,2'-地特克辛衍生物的激发态性质进行了比较研究，以分析此类损失通道对分子堆积和分子间相互作用的依赖性。在纯净的单晶中，2,2'-二trace的吸收光谱和发射光谱与并四苯的吸收光谱和发射光谱有大约150 meV的红移，而在分散的分子分散在结晶蒽基质中的情况下，两种染料的发射光谱实际上相同模式。与并四苯不同，2,2'-二trace单晶光致发光（PL）和基于实验单晶结构的时变密度泛函理论（DFT）计算中没有延迟荧光，表明激发的单重态能量下降以下E（S ₁）= 2 E（T ₁）阈值。同时，时间分辨的温度相关PL数据显示了分子S ₁状态和激发的二聚体状态之间的相互作用，该状态有效地填充在10 K以上。冷却后，2,2'-双trace晶体的光致发光性能优于并四苯。的数量级超过一个数量级，并突出了分子设计的潜力，这里是两个十四碳烯的共价连接，可保留单个生色团的光学性质，同时可决定性地改善其在晶体聚集体中的光物理性质。

更新日期：2020-09-10

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