High-Efficiency Circularly Polarized Luminescence from Chiral Luminescent Liquid Crystalline Polymers with Aggregation-Induced Emission Properties

Abstract

Circularly polarized luminescent materials play an increasingly important role in display equipment and optical apparatuses. Herein, we design and synthesize a kind of luminescent liquid crystalline polymer with both chirality and aggregation-induced emission groups, namely, poly­(4-cholesterol formate-oxygen-tetraphenylethylene-methacrylate) (PT-Chol). Polarized light microscopy and X-ray scattering results show that the polymer forms a layered structure. Because of the existence of the tetraphenylethylene luminogen, the polymer shows highly efficient circularly polarized luminescence (CPL) properties with a luminescence dissymmetry factor (g lum) of ∼+0.45 after blending a specified amount of 4-cyano-4′-pentyl biphenyl (5CB), although the pure polymer does not show any CPL behavior in the solid state. A further experimental result shows that the mixture of PT-Chol and 5CB can form a chiral nematic liquid crystal (N*-LC) or smectic C* (Sm C*) phase in low concentration, but the complete dissolution of PT-Chol in 5CB does not result in the development of CPL properties. Gradually increasing the concentration of PT-Chol leads to the development of aggregation-enhanced emission behavior in the 5CB solution, which results in highly efficient CPL properties in the Sm C* phase. At the same time, the obtained circularly polarized luminescent material shows excellent stability, which is conducive to its applications in optoelectronic devices.

Frontiers in circularly polarized luminescence: molecular design, self-assembly, nanomaterials, and applications

“…Inspired by the circularly polarized reflection in nature and living organisms involving the formation of self-organizing chiral nematic photonic structures [147][148][149], CPL-active polymers were prepared by taking chiral LCs and crystalline polymers as CPL filters [150][151][152][153][154][155]. In these systems, interand intra-molecular interactions between chiral and fluorescent substances are no longer indispensable, and the obtained materials generally possess high g lum values.…”

Liquid Crystal Templated Chiral Plasmonic Films with Dynamic Tunability and Moldability

“…Thus, it is not surprising that soft organic matter has been a primary choice, owing to its processability, self-assembly, and possibilities for mesoscopic morphology control. [7][8][9][10] A transformative leap in advancing the properties and applications of chiral thin films is currently foreseen by incorporating inorganic nanoscale building blocks, which exhibit enhanced light-matter interactions. [11][12][13][14][15] Chiral thin films comprising semiconductor nanostructures have been extensively studied toward increasing efficiency, tuning wavelength range, and unlocking new applications.…”

Polymersomes with a smectic liquid crystal structure and AIE fluorescence

“…Note that in a luminescent LC polymer reported recently where both TPE and Chol moieties were connected in the same side group, the presence of TPE did influence the LC phases and circularly polarized luminescence properties were achieved. 43…”