The effect of fluorescence of perylene red dyes on the contrast ratio of LCD color filters

• Six perylene-based dyes were synthesized and color filters were prepared with each dye.
• The fluorescence and optical properties of the synthesized dyes and the prepared color filters were evaluated.
• The minimum brightness of the color filters showed a similar trend to the total emission intensity of the dyes.
• Color filters fabricated with strongly fluorescent dyes exhibited high minimum brightness and low contrast ratio.

Dye-based and pigment-dye hybrid color filters are recommended to overcome the drawbacks such as light scattering of traditional pigment-based color filters. However, dyes used as colorants for LCD color filters may exhibit strong fluorescence. Fluorescence lowers the contrast ratio of color filters by increasing brightness in the full-black state and affects optical performance of displays. In this study, the correlation between dye fluorescence and the optical properties of color filters was investigated. Six perylene-based dyes were synthesized, and dye-based and pigment-dye hybrid color filters were prepared with each dye. The fluorescence properties of the synthesized dyes in solution and the prepared color filters were evaluated. The maximum brightness and the contrast ratio of the color filters were measured, from which the minimum brightness of the color filters was calculated. All dye-based and pigment-dye hybrid color filters showed greater minimum brightness than pigment-based one due to emission in the visible region.