We demonstrate a systematic visualization of the unique photophysical and fluorescence anisotropic properties of polyfluorene coplanar conformation (β-conformation) using time-resolved scanning confocal fluorescence imaging (FLIM) and fluorescence anisotropy imaging microscopy (FAIM) measurements. We observe inhomogeneous morphologies and fluorescence decay profiles at various micrometer-sized regions within all types of polyfluorene β-conformational spin-coated films. Poly(9,9-dioctylfluorene-2,7-diyl) (PFO) and poly[4-(octyloxy)-9,9-diphenylfluoren-2,7-diyl]-co-[5-(octyloxy)-9,9-diphenylfluoren-2,7-diyl] (PODPF) β-domains both have shorter lifetime than those of the glassy conformation for the longer effective conjugated length and rigid chain structures. Besides, β-conformational regions have larger fluorescence anisotropy for the low molecular rotational motion and high chain orientation, while the low anisotropy in glassy conformational regions shows more rotational freedom of the chain and efficient energy migration from amorphous regions to β-conformation as a whole. Finally, ultrastable ASE threshold in the PODPF β-conformational films also confirms its potential application in organic lasers. In this regard, FLIM and FAIM measurements provide an effective platform to explore the fundamental photophysical process of conformational transitions in conjugated polymer.

中文翻译：

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聚芴β构象膜的光物理和荧光各向异性行为

我们展示了使用时间分辨扫描共聚焦荧光成像（FLIM）和荧光各向异性成像显微镜（FAIM）测量的聚芴共面构象（β-构象）独特的光物理和荧光各向异性特性的系统可视化。我们观察到在所有类型的聚芴β-构象旋涂膜中不同微米尺寸区域的不均匀形态和荧光衰减曲线。聚（9,9-二辛基芴-2,7-二基）（PFO）和聚[4-（辛氧基）-9,9-二苯基芴-2,7-二基] -co对于更长的有效共轭长度和刚性链结构，-[5-（辛氧基）-9,9-二苯基芴-2,7-二基]（PODPF）β结构域的寿命均比玻璃状构型的寿命短。此外，对于低分子旋转运动和高链取向，β构象区具有较大的荧光各向异性，而玻璃状构象区的低各向异性表现出更大的链旋转自由度以及从无定形区到整个β构象的有效能量迁移。最后，PODPFβ构象薄膜中的超稳定ASE阈值也证实了其在有机激光器中的潜在应用。在这方面，FLIM和FAIM测量提供了一个有效的平台，以探索共轭聚合物中构象转变的基本光物理过程。