Circularly polarized luminescence in chiral nematic liquid crystals: generation and amplification

Circularly polarized luminescent materials have reached a thriving stage due to their potential applications in various research fields. However, the most important parameter of circularly polarized luminescence, luminescence dissymmetry factor (g(lum)), is unsatisfactory to date, particularly for organic small molecules. Thus, obtaining large g(lum) values is an emergent and critical challenge in the CPL research field, and various strategies have consequently been proposed, including supramolecular self-assembly or co-assembly, energy transfer or charge transfer hybrid chiral systems, aggregation-induced emission chiral luminophores, and so forth. Nevertheless, among all these strategies, chiral nematic liquid crystals (N*LCs) possess incomparable advantages in acquiring high g(lum) values, because of their unique optical properties and excellent generality. In this review, we systematically review the recent progress of CPL-active N*LCs and provide a short perspective on their further applications. We envisage that N*LCs will play a more and more important role in the CPL research field and this review will attract more researchers to this field.