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

Guodan Wei; Mengfan Lu; Kai Feng; Sijia Ma; Yuqian Jiang; Zhaoxia Jin

doi:10.1021/acsomega.3c02969

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

ACS Omega. 2023 Jun 12;8(25):23191-23201. doi: 10.1021/acsomega.3c02969. eCollection 2023 Jun 27.

Authors

Guodan Wei¹, Mengfan Lu¹, Kai Feng¹, Sijia Ma^{2

3}, Yuqian Jiang³, Zhaoxia Jin¹

Affiliations

¹ Key Laboratory of Advanced Light Conversion Materials and Biophotonics, Department of Chemistry, Renmin University of China, 100872 Beijing, People's Republic of China.
² Beijing National Laboratory for Molecular Science (BNLMS), Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, ZhongGuanCun North First Street 2, 100190 Beijing, People's Republic of China.
³ Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nano-Science and Technology, 100190 Beijing, People's Republic of China.

Abstract

The chiral nematic nanostructure formed from cellulose nanocrystal (CNC) self-assembly has shown great potential as a matrix for generating circularly polarized luminescent (CPL) light with a high dissymmetry factor. Exploring the relationship between the device composition and structure and the light dissymmetry factor is crucial to a common strategy for a strongly dissymmetric CPL light. In this study, we have compared the single-layered and double-layered CNC-based CPL devices with different luminophores, such as rhodamine 6G (R6G), methylene blue (MB), crystal violet (CV), and silicon quantum dots (Si QDs). We demonstrated that forming a double-layered structure of CNCs nanocomposites is a simple but effective pathway for enhancing the CPL dissymmetry factor for CNC-based CPL materials containing different luminophores. The |g_lum| values of double-layered CNC devices (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, and 2.78 times for CV series. The different enhancement degrees of these CNC layers with a similar thickness may be due to the different pitch numbers in the chiral nematic liquid crystal layers whose photonic band gap (PBG) has been modified to match the emission wavelengths of dyes. Furthermore, the assembled CNC nanostructure has great tolerance to the addition of nanoparticles. Gold nanorods coated with the SiO₂ layer (Au NR@SiO₂) were added for enhancing the dissymmetry factor of MB in CNC composites (named MAS devices). When the strong longitudinal plasmonic band of the Au NR@SiO₂ matched the emission wavelength of MB and the PBG of assembled CNC structures 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 it a universal platform for developing strong CPL light sources with a high dissymmetry factor.