Broadband Reflective Cholesteric Liquid Crystals for Low‐Blue Circularly Polarized Light Generation in the Visible Region

In this work, a polymerizable chiral liquid-crystal monomer was first synthesized from inexpensive biomass-derived cholesterol through a simple transformation. Co-assembling this chiral monomer with a polymerizable achiral liquid-crystal monomer and followed by initiator-free photopolymerization, yielded a cholesteric liquid-crystal (CLC) material YMZ-5 featuring a broad reflection band in the visible region with blue-selectivity. After removal of the quartz substrates, the material forms a flexible film with good thermal stability. Due to Bragg reflection, under transmission mode, YMZ-5 efficiently converts 510-700 nm unpolarized light into right-handed circularly polarized (R-CP) light with dissymmetry factors (g_lum) of -1.6 and even reaching up to -2.0. Placed behind achiral zero-blue aqueous solutions, YMZ-5 enabled multicolour zero-blue circularly polarized photoluminescence, generating exclusively R-CP light with |g_lum| values exceeding 1.6. Additionally, under reflection mode, YMZ-5 efficiently converts unpolarized ambient light into 510-700 nm low-blue left-handed circularly polarized (L-CP) light. Therefore, YMZ-5 exhibited distinctly different colors under varying backgrounds and circular polarizers. Leveraging these behaviors, molecular logic gate and information encryption-decryption were realized. Furthermore, a conceptual design for a low-blue circularly polarized display device was also demonstrated.