Sensitization effects of fluorescent dichroic dyes in a nematic liquid crystal and fluorescence colors

In a nematic liquid crystal (LC), the excitation energy of an ultraviolet light (360 nm) is efficiently transferred to yellow fluorescent dye via blue fluorescent sensitizer, to enhance yellow fluorescence of the dichroic dye. The LC can emit white fluorescence when yellow and blue fluorescent dyes are mixed at suitable concentrations. In the homogeneously aligned cell with the fluorescent nematic LC, fluorescent dye molecules reorient along the applied electric field with LC molecules when the voltage is applied to the LC cell. With the increase of the voltage, the fluorescent intensity decreases without changing the fluorescent color. The contrast ratio at 0 and 8 V is about 6.5.