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首页> 外文期刊>Physical chemistry chemical physics: PCCP >Dynamics of fluorescence depolarisation in star-shaped oligofluorene-truxene molecules
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Dynamics of fluorescence depolarisation in star-shaped oligofluorene-truxene molecules

机译：星形低聚芴-二甲苯分子中荧光去极化的动力学

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摘要

Star-shaped molecules are of growing interest as organic optoelectronic materials. Here a detailed study of their photophysics using fluorescence depolarisation is reported. Fluorescence depolarisation dynamics are studied in branched oligofluorene-truxene molecules with a truxene core and well-defined three-fold symmetry, and are compared with linear fluorene oligomers. An initial anisotropy value of 0.4 is observed which shows a two-exponential decay with time constants of 500 fs and 3-8 ps in addition to a long-lived component. The femtosecond component is attributed to exciton localisation on one branch of the molecule and its amplitude reduces when the excitation is tuned to the low energy tail of the absorption spectrum. The picosecond component shows a weak dependence on the excitation wavelength and is similar to the calculated rate of the resonant energy transfer of the localised exciton between the branches. These assignments are supported by density-functional theory calculations which show a disorder-induced splitting of the two degenerate excited states. Exciton localisation is much slower than previously reported in other branched molecules which suggests that efficient light-harvesting systems can be designed using oligofiuorenes and truxenes as building blocks.
机译：星形分子作为有机光电子材料越来越受到关注。这里报道了使用荧光去极化对其光物理性质的详细研究。在具有萜烯核和明确定义的三重对称性的支链低聚芴-茂烯分子中研究了荧光去极化动力学，并将其与线性芴低聚物进行了比较。观察到初始各向异性值为0.4，该值显示了一个双指数衰减，除了寿命较长的分量外，还具有500 fs和3-8 ps的时间常数。飞秒分量归因于激子在分子一个分支上的定位，当将激发调谐到吸收光谱的低能尾部时，其幅度减小。皮秒分量显示出对激发波长的弱依赖关系，类似于分支之间局部激子的共振能量转移的计算速率。这些分配得到密度泛函理论计算的支持，该算法显示了两种简并激发态的无序诱导分裂。激子的定位要比以前在其他支链分子中报道的要慢得多，这表明可以使用寡聚富勒烯和戊二烯作为构件来设计有效的光收集系统。

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