The displaced and distorted harmonic oscillator model, which has been proven to be appropriate in calculating vibronic spectra, is employed to treat the emission spectrum of title molecules in combination with a thermal vibration correlation function. The calculated results indicate that the main peak of the emission spectrum is visibly impacted by the normal modes with lower frequencies and that the shoulder peak is originated from the middle-frequency modes. On the level of time-dependent density functional theory (TDDFT), the calculated fluorescence lifetimes of TTM-3NCz and TTM-3PCz are 22.1 and 26.0 ns, respectively, which happen to coincide with the observed values of TTM-3NCz (17.2 ns) and TTM-3PCz (21.2 ns). The above data indicate that both the calculated radiative decay rates are reasonable at room temperature. Furthermore, we investigate the influence of the Duschinsky effect on the fluorescence quantum efficiency (FQE). When it is considered, the predicted FQE of the TTM-3NCz molecule is only 0.11%, and the observed value (49% in toluene) deviates significantly. If we ignore the Duschinsky effect, the FQE of TTM-3NCz increases dramatically to 41.8%. For the TTM-3PCz molecule (the FQE is 46% in toluene), the calculated FQE is 0.042% with the Duschinsky effect and increases to 45.2% without the Duschinsky effect. This phenomenon might be related to external factors and the nature of the TDDFT only considering a single configuration. In addition, the fluorescent properties of the fluorinated TTM-3NCz molecules are studied predictably. The obtained results show that the perfluorinated TTM-3NCz shows better luminous performance due to larger oscillator strength. Finally, the dimers, which are composed of both single title molecules, are explored theoretically to determine how they impact the fluorescent property; however, the effect can be nearly eliminated because of the small binding energies.

中文翻译：

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具有双重态基态的创新有机电致发光材料：理论研究。

位移和扭曲的谐波振荡器模型已被证明适用于计算振动光谱，结合热振动相关函数来处理标题分子的发射光谱。计算结果表明，发射频谱的主峰明显受到较低频率的正常模式的影响，而肩峰则源于中频模式。在时变密度泛函理论（TDDFT）的水平上，TTM-3NCz和TTM-3PCz的荧光寿命分别为22.1 ns和26.0 ns，与TTM-3NCz的观测值（17.2 ns）吻合。和TTM-3PCz（21.2 ns）。以上数据表明，在室温下计算出的两个辐射衰减率都是合理的。此外，我们研究了Duschinsky效应对荧光量子效率（FQE）的影响。考虑到这一点，TTM-3NCz分子的预测FQE仅为0.11％，观察值（甲苯中为49％）显着偏离。如果我们忽略Duschinsky效应，则TTM-3NCz的FQE会急剧增加至41.8％。对于TTM-3PCz分子（甲苯中的FQE为46％），在Duschinsky效应下，计算出的FQE为0.042％，在没有Duschinsky效应下，计算得出的FQE增加到45.2％。仅考虑单个配置，此现象可能与外部因素和TDDFT的性质有关。另外，可预测地研究了氟化的TTM-3NCz分子的荧光性质。获得的结果表明，由于更大的振荡器强度，全氟化的TTM-3NCz显示出更好的发光性能。最后，从理论上探讨了由两个单一标题分子组成的二聚体，以确定它们如何影响荧光性质。但是，由于结合能小，几乎可以消除这种影响。