Exploring the Core Parameters of CNC-Based Chiral Nematic Structures for Enhancing the Dissymmetry Factor of Right-Handed Circularly Polarized Luminescence

The chiral nematic nanostructure formed from cellulosenanocrystal(CNC) self-assembly has shown great potential as a matrix for generatingcircularly polarized luminescent (CPL) light with a high dissymmetryfactor. Exploring the relationship between the device compositionand structure and the light dissymmetry factor is crucial to a commonstrategy for a strongly dissymmetric CPL light. In this study, wehave compared the single-layered and double-layered CNC-based CPLdevices with different luminophores, such as rhodamine 6G (R6G), methyleneblue (MB), crystal violet (CV), and silicon quantum dots (Si QDs).We demonstrated that forming a double-layered structure of CNCs nanocompositesis a simple but effective pathway for enhancing the CPL dissymmetryfactor for CNC-based CPL materials containing different luminophores.The |g (lum)| values of double-layered CNCdevices (dye@CNC5||CNC5) versus that of single-layered devices (dye@CNC5)are 3.25 times for Si QDs, 3.7 times for R6G, 3.1 times for MB, and2.78 times for CV series. The different enhancement degrees of theseCNC layers with a similar thickness may be due to the different pitchnumbers in the chiral nematic liquid crystal layers whose photonicband gap (PBG) has been modified to match the emission wavelengthsof dyes. Furthermore, the assembled CNC nanostructure has great toleranceto the addition of nanoparticles. Gold nanorods coated with the SiO2 layer (Au NR@SiO2) were added for enhancing thedissymmetry factor of MB in CNC composites (named MAS devices). Whenthe strong longitudinal plasmonic band of the Au NR@SiO2 matched the emission wavelength of MB and the PBG of assembled CNCstructures simultaneously, the increase in the g (lum) factor and quantum yield of MAS composites was obtained.The good compatibility of the assembled CNC nanostructures makes ita universal platform for developing strong CPL light sources witha high dissymmetry factor.

Automated summary

The chiral nematic nanostructure formed from cellulosenanocrystal (CNC) self-assembly has great potential for generating circularly polarized luminescent (CPL) light. This study compares single-layered and double-layered CNC-based CPL devices with different luminophores and demonstrates that a double-layered CNC structure enhances the CPL dissymmetry factor. The introduced gold nanorods coated with SiO2 layer further enhance the dissymmetry factor and quantum yield of the CNC composites.