Controlling Supramolecular Chirality and Circularly Polarized Luminescence in Co-Assembled Copolymers via Fluorene-Content Engineering
Precise control over supramolecular chirality and circularly polarized luminescence (CPL) is achieved through fluorene-content engineering of alkylated fluorene-quinoxaline copolymers. By systematically varying the fluorene ratio, three polymers (F8QX, F8QX-II, F8QX-III) are synthesized and co-assembled with a chiral inducer (R/S-5011). Thermal annealing induces highly ordered, crosslinked superstructures with strong chiroptical activity, where the dissymmetry factor (g_lum) decreases with increasing fluorene content. The optimal system, (F8QX)0.7-(R/S-5011)0.3, achieves a high |g_lum| of 0.52. Structural analyses and molecular dynamics (MD) simulations reveal that lower fluorene ratios facilitate tighter π–π stacking and more efficient chirality amplification. This system further serves as an excellent host for a narrowband multi-resonance thermally activated delayed fluorescence (TADF) emitter (DBN-ICZ) via Förster resonance energy transfer, yielding ternary co-assemblies with narrowband green emission (FWHM = 25 nm) and strong CPL with g_lum of 0.43. Circularly polarized organic light-emitting diodes (CP-OLEDs) based on (F8QX)0.7-(R/S-5011)0.3-(DBN-ICZ)0.005 exhibit yellow circularly polarized electroluminescence with |g_EL| value of 0.12. This work provides a comprehensive strategy integrating molecular design, hierarchical assembly, and energy transfer toward high-performance chiral optoelectronic materials.