Circularly polarized organic room temperature phosphorescence activated by liquid crystalline polymer networks

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 11; no. 12; pp. 414 - 4111
• Main Authors: Huang, Ao, Huang, Jiang, Luo, Hui-Ying, Luo, Zhi-Wang, Wang, Pu, Wang, Ping, Guan, Yan, Xie, He-Lou
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 23.03.2023
• Subjects: Benzoates; Carbazoles; Carbonyls; Circular polarization; Crosslinking; Dichroism; Liquid crystal polymers; Liquid crystals; Luminescence; Monomers; Phosphorescence; Room temperature; Self-assembly; Ultraviolet radiation
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d2tc04829a

Circularly polarized luminescent (CPL) materials have attracted much attention due to their potential applications in 3D imaging, anti-counterfeiting, etc. However, it is still a great challenge to achieve circularly polarized room temperature phosphorescence (CPRTP). In this work, a series of chiral compounds (denoted as (R/S)-B- n -CzO, n = 4, 8 and 12) are successfully designed and synthesized combining binaphthol and carbazole-dibenzofuran for the fabrication of CPRTP materials. The resultant compounds show excellent luminescence behaviour in both solution and the solid state with absolute fluorescence quantum yields of up to 52.97%. Due to the existence of a chiral group, these compounds show circular dichroism (CD) in solution, but no CPL behaviour is observed. Furthermore, this kind of compound is doped into a commercial liquid crystalline monomer (2-methyl-1,4-phenylene bis (4-(((4-(acryloyloxy) butoxy) carbonyl) oxy) benzoate, LC-242)) to fabricate CPRTP materials through liquid crystal (LC) self-assembly and a confined phosphorescent moiety by UV light cross-linking the monomer. As a result, the obtained liquid crystalline polymer network shows CPRTP behaviour with the largest luminescence dissymmetry ( g lum ) value of +0.098. This provides a meaningful design idea for the preparation of CPRTP materials. Circularly polarized organic room temperature phosphorescence (CPRTP) with g max = +0.098 was activated by the rigid environment of an in situ cross-linked liquid crystalline polymer network.