Microscopic observations of RGB circularly polarized luminescence from solid microspheres with liquid crystalline molecular order

Micro-particles with an internal helical liquid crystalline (LC) molecular order serve as efficient and highly compact circularly polarized luminescence (CPL) emitters. However, the coupling between CPL emission and the interior LC molecular order remains poorly understood at the single particle level. Here, we synthesized microspheres from a LC monomer RM23 together with a fluorescent dye and a chiral additive (R/S-BPy) and investigated their CPL properties. Polarized optical microscopy and angle-dependent CPL observations at a single-particle level revealed randomly distributed one-handed helical domains in each sphere, leading to CPL emission with an average dissymmetry factor value |glum| of 0.05 regardless the observation angle. The color of the CPL emission is tunable in the range of 450 to 700 nm by varying the fluorescent dyes doped in the spheres.