Yu Meng-Na, Soleimaninejad Hamid, Lin Jin-Yi, Zuo Zong-Yan, Liu Bin, Bo Yi-Fan, Bai Lu-Bing, Han Ya-Min, Smith Trevor A, Xu Man, Wu Xiang-Ping, Dunstan Dave E, Xia Rui-Dong, Xie Ling-Hai, Bradley Donal D C, Huang Wei
Centre for Molecular Systems and Organic Devices (CMSOD), Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications , 9 Wenyuan Road, Nanjing 210023, China.
ARC Centre of Excellence in Exciton Science, School of Chemistry, The University of Melbourne , Parkville, Victoria 3010, Australia.
J Phys Chem Lett. 2018 Jan 18;9(2):364-372. doi: 10.1021/acs.jpclett.7b03148. Epub 2018 Jan 9.
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.
我们通过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，展示了聚芴共面构象（β-构象）独特的光物理和荧光各向异性特性的系统可视化。我们在所有类型的聚芴β-构象旋涂膜内的各种微米级区域观察到不均匀的形态和荧光衰减曲线。聚（9,9-二辛基芴-2,7-二亚基）（PFO）和聚[4-（辛氧基）-9,9-二苯基芴-2,7-二亚基]-共-[5-（辛氧基）-9,9-二苯基芴-2,7-二亚基]（PODPF）β-域由于有效共轭长度更长和链结构刚性，其寿命均比玻璃态构象的寿命短。此外，β-构象区域由于分子旋转运动低和链取向高而具有更大的荧光各向异性，而玻璃态构象区域的低各向异性表明链具有更多的旋转自由度以及从非晶区域到整体β-构象的有效能量迁移。最后，PODPFβ-构象膜中的超稳定受激发射损耗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，用于探索共轭聚合物中构象转变的基本光物理过程。
