Perylene-based modified dye blends with sunset yellow for tunable anisotropic optical films

This study reports the successful synthesis of PDI-HCl, followed by its co-assembly with Sunset Yellow molecules to prepare a solution. This solution was subsequently coated onto a glass substrate, leading to an enhancement in the polarization efficiency of the resulting PDI-HCl thin film within the 447–567 nm wavelength range. The underlying mechanism was elucidated through comprehensive characterization using XRD, SEM, and POM. The liquid crystalline phase behavior, phase separation, and intermolecular interactions between Sunset Yellow (SSY) and PDI in aqueous solution were systematically investigated across a range of concentration ratios. The results demonstrate that while both components individually can form well-defined columnar crystalline structures within specific concentration ranges, their combination disrupts this self-assembly unless an optimal ratio is identified. This disruption compromises the film's molecular orientation and polarization efficiency. Notably, within the447–567 nm spectral window, a binary system with PDI-HCl as the host and Sunset Yellow as the guest (at a 19:1 molar ratio) exhibits a pronounced synergistic enhancement in absorption, with intensity far exceeding that of either component alone. At this optimized ratio, the polarization efficiency reaches 97.91%.