Modulating the molecular structure of azo-pyridone dyes via morpholine and pyridine substituents to enhance their high-performance in color filters

Azo-pyridone dyes are attractive candidates for high-performance color filters owing to their rigid conjugated frameworks and high thermal stability. However, their practical application is often limited by strong intermolecular interactions that promote aggregation, resulting in broadened absorption profiles and compromised optical quality in thin films. Herein, we demonstrate that introducing N-heterocyclic substituents, morpholine and pyridine, onto the azo-pyridone core effectively disrupts π–π stacking and suppresses aggregation, enabling uniform dye dispersion in poly(methyl methacrylate) (PMMA) matrices. The resulting dye-PMMA composite films exhibit high optical transmittance (>90%), significantly improved yellow color purity and excellent thermal and photostability (Δ E < 3). Combined experimental and density functional theory (DFT) analyses reveal that the heterocyclic substituents modulate the molecular electrostatic potential distribution and reduce intermolecular interaction strength, accounting for the suppressed aggregation behaviour. Both morpholine and pyridine proved effective, confirming the generality of this substitution strategy. This work provides a practical molecular design approach based on N-heterocyclic modification for developing high-performance azo-pyridone dyes for advanced color filter applications.