Photophysical and Fluorescence Anisotropic Behavior of Polyfluorene β-Conformation Films

Meng Na Yu, Hamid Soleimaninejad, Jin Yi Lin, Zong Yan Zuo, Bin Liu, Yi Fan Bo, Lu Bing Bai, Ya Min Han, Trevor A. Smith, Man Xu, Xiang Ping Wu, Dave E. Dunstan, Rui Dong Xia, Ling Hai Xie, Donal D.C. Bradley, Wei Huang

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

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.
Original languageEnglish (US)
JournalJournal of Physical Chemistry Letters
Volume9
Issue number2
DOIs
StatePublished - Jan 18 2018
Externally publishedYes

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