Synthesis of dis-azo black dyes for electrowetting displays

This study was to design and synthesize a series of dis-azo dyes derived from p-n-alkyl aniline by introducing different alkyl group resulted in having high solubility in linear alkanes solvents, even absorption intensity of visible wavelengths. Results indicated that elementary properties of black oil ink were (1) non-polar; (2) low viscosity (<3.0 cps); (3) specified surface tension (<30 mN/m); (4) intensity of visible absorption uniformly covering 400–800 nm; (5) FoM equal to 100–1000; (6) hue close to standard black (L = 0, a = 0, b = 0). We can conclude that dis-azo black dyes fulfills elementary conditions of colored oil ink for electrowetting display.

► The electrowetting technology with high reflectivity, high contrast, and fast response speed. ► Color electrowetting display is manufactured by using black oil ink as an absorbing switch. ► Conventional dis-azo black dyes possess poor solubility in linear alkanes. ► Previous researches have focused on designing of electrowetting devices. ► These dis-azo black dyes were resulted in having high solubility and neutral hue.