Enhanced Circularly Polarized Luminescence Modulation Using Dichroic Conjugated Polymer in Cholesteric Liquid Crystals

Abstract Negative dichroic dyes are crucial for enhancing the brightness of liquid crystal displays (LCDs) and modulating circularly polarized luminescence (CPL) in cholesteric liquid crystals (CLCs) through supramolecular co‐assembly. However, the majority of fluorescent molecules exhibit positive dichroism, and there is a limited understanding of designing negative dichroic molecules. In this paper, a novel design principle is proposed to construct the negative dichroic polymer by introducing through space charge transfer (TSCT) side chain structure to the polymer backbone. Specifically, two conjugated polymers (P1, P2) are synthesized using the Suzuki coupling reaction of two donor‐acceptor (D‐A) type monomers (V‐type M1 and I‐type M2) with fluorenyl monomer. P1 exhibits negative dichroism, and its orientational order parameter (S_F) is up to S_FP1 = –0.18. On the contrary, P2 is positive dichroism (S_FP2 = + 0.27). This variation arises from the differing orientations of the rigidly functional side chains (S_FM1 = + 0.07; S_FM2 = + 0.31), which affect the alignment (parallel or perpendicular) of the polymer backbone toward CLCs molecules. This phenomenon facilitates controllable dichroism and precisely modulates the handedness of CPL signals, thereby facilitating the successful implementation of multidimensional information encryption systems in CLCs.