Induced blue, green, and red-colour circularly polarized luminescence from single dye-doped homochiral poly(lactic acid) microspheres†

Abstract

Circularly polarized luminescence (CPL) can be induced by doping an achiral fluorescent dye into a chiral polymer matrix. Here, we demonstrate the supramolecular self-assembly of chiral poly(L-lactic acid) (PLLA) with the fluorescent dye, 9,10-bis(phenylethynyl)anthracene (BPEA), forming microspheres that generate CPL. As the BPEA concentration increases, the fluorescent colour shifts from blue to green and red, suggesting the formation of BPEA dimers and J-aggregates. The highest luminescent dissymmetry factor (g_lum) of 3.1 × 10⁻² was obtained from the microsphere suspension at the BPEA/PLLA ratio of 0.1.