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Tuning the circularly polarized luminescence of polymer-stabilized cholesteric liquid crystal films using chiral dopants†
Xiaohui Lu,Ziqing Zhou,Baining Ni,Hongkun Li,Baozong Li,Wei Liu,Yong Wang,Yonggang Yang
Journal of Materials Chemistry C Pub Date : 04/22/2022 00:00:00 , DOI:10.1039/D2TC00326K
Abstract

In this work, a tetraphenylethene and imidazo[1,2-a]pyridine-attached difluoroboron β-diketonate triad TPE-BF2acac-MeIP has been synthesized. TPE-BF2acac-MeIP exhibits significant aggregation-induced emission and mechanofluochromism properties and can be utilized for latent fingerprint visualization. Due to its strong emission and high quantum efficiency, dye TPE-BF2acac-MeIP is embedded into polymer-stabilized cholesteric liquid crystals (PSCLCs). Circularly polarized luminescence (CPL) with large dissymmetry factors (|glum| up to 0.61) and high emission quantum yields (ΦF up to 64.2%) were obtained. Circular dichroism results indicated that the dye preferred to form conformations in one handedness (M- or P-) under chiral surroundings. CPL performance was dominated by the matching extent of emission of the dye with chiral conformations/stackings and selective Bragg reflection of the PSCLC film. In addition, via changing the dye concentration and film thickness, it was found that the inner filter effect also played a role in the |glum| value. This work not only gives us a better understanding of the origin of the CPL behaviour, but also lays foundations for the applications of CPL materials in three-dimensional optical displays, photoelectric devices, and information storage and processing.

Graphical abstract: Tuning the circularly polarized luminescence of polymer-stabilized cholesteric liquid crystal films using chiral dopants
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