Dual Stimuli-Responsive High-Efficiency Circularly Polarized Luminescence from Light-Emitting Chiral Nematic Liquid Crystals

Abstract

Considerable luminescence dissymmetry factor (g lum) is vital for application implementation of circularly polarized luminescence (CPL) materials. Moreover, a dual CPL switch has promising prospects in high-security encryption and sensor devices. Herein, we designed and synthesized an emissive chiral nematic liquid crystal (N*-LC) by doping a luminescent chiral additive (NO2-CS-C6-Chol) into a nematic liquid crystal (5CB). The helical assembly structure produced by inducing the formation of N*-LC endows the prepared emissive N*-LC with a larger g lum value. With the increase of the doping concentration from 1 to 10 wt %, the helical pitch (P) of N*-LC gradually decreases from 25.48 to 3.92 μm. The corresponding g lum value increases first, reaches the maximum value (−0.38) at 6 wt %, and then decreases slightly. Further, the prepared emissive N*-LC doped with 6 wt % NO2-CS-C6-Chol is injected into an indium-tin oxide (ITO)-coated LC cell, to which a direct current (DC) electric field is applied. The g lum value can be repeatedly shuttled between the “on” and “off” state by adjusting the applied voltage. Meanwhile, owing to the inherent thermal dependence of the liquid crystal phase structure, the g lum value can also be switched between the on and off state by regulating the temperature. Therefore, an electrically controlled and thermocontrolled dual CPL switching device is successfully constructed.

Generating circularly polarized luminescence from clusterization‐triggered emission using solid phase molecular self-assembly

“…13 ). This value is 10–1000 times higher than those generated from many conventional conjugated organic emitters since they often have a g lum of 10 −3 –10 −5 70 – 72 . To the best of our knowledge, this is the first purely organic CTE based CPL that has ever been reported, indicating it is very promising in creating CPL with green and sustainable materials.…”

Blue-Shifting Mechanofluorochromic Luminescent Behavior of Polymer Composite Films Using Gelable Mechanoresponsive Compound

“…Cholesterol, a typical biocompatible functional group, can be used to mimic lipid bilayers and interact with various functional materials in living organisms. In addition, cholesterol has many optically active sites; thus, it is expected to have extended functions beyond its use as a gelator, such as circularly polarized light emission and higher order LCs [28,29]. However, these functions are still under study.…”

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

“…In the past several years, there have been more and more reports on chiral emissive liquid crystals (N*-LCs) as CPL-active materials. These materials can self-assemble as highly regular helical arrangement in LC medium after annealing treatment as a result of the LC-templated molecular reorientation, which is beneficial for the enlarged effect of the induced CPL signals [101][102][103][104][105][106][107]. In 2020, Cheng's group [101] realized the recyclable CPL response behavior in N*-LCs doped with the axially chiral molecules (R/S)-37 (Figure 12a).…”