Synthesis of quenchers to control the fluorescence of Rhodamine B and improve the contrast ratio of blue filters for LCDs

In this study, seven quenchers (derived from either anthraquinone, phthalimidylazo, or dipyrromethene chromophores) were prepared as candidates for additives to suppress fluorescence in blue colour filters and thus improve their contrast ratio. To reduce fluorescence effectively, quenchers must have typical properties such as spectral compatibility by which the absorbance spectrum of the quencher overlaps the fluorescence emission spectrum, exhibit high molar extinction coefficients, and exert little influence on the colour of the blue filter. The seven quenchers possessed absorption maxima of approximately 570–620 nm and reduced fluorescence (by more than 24%). Those quenchers tested in filter coatings increased their contrast ratios by about 50%. They thus effectively quenched fluorescence of the blue filter but without greatly affecting the chromaticity coordinates of the filters.