The synthesis of thermally-stable red dyes for LCD color filters and analysis of their aggregation and spectral properties

Three thermally-stable red dyes of azo, quinacridone and perylene derivatives were synthesized and dye-based color filters were manufactured for use in liquid crystal displays. The aggregation behavior of the dyes and their spectral properties in film state were investigated using field emission scanning electron microscopy and concentration-dependent spectroscopy. Aggregate size was related to the geometry of the three dye types rather than their size, with average aggregate sizes ranging from 35 nm (azo), 80 nm (quinacridone) to 25 nm (perylene). Aggregation behavior affected the spectral property of the red color filter, resulting in weaker and broader transmittance spectrum with higher aggregation.