Stable and Efficient Fluorescent Red and Green Dyes for External and Internal Conversion of Blue OLED Emission

A series of diphenylamine substituted coumarin, (dicyanomethylene)pyran, and benzophenoxazone dyes has been synthesized and their optical and electroluminescent properties, thermal and photo-oxidative stabilities, and potential as red and green dopants for organic lightemitting diode (OLED) displays or down-conversion fluorescent dyes for external colorconverters has been investigated. The incorporation of the bulky phenyl groups in these dyes delays the onset of concentration quenching. The improved photoluminescent efficiency and photo-oxidative stability of these dyes make them excellent candidates for external colorconversion. The improved electroluminescence and power efficiencies and enhanced thermal stabilities of 3-(2'-benzimidazolyl)-7-(diphenylamino)-2H-1-benzopyran-2-one (C7S) as well as its Commission Internationale d’Eclairage (CIE) coordinates suggests its use as a green dopant in OLED devices.