Bright and ultimately pure red electrophosphorescent diode bearing diphenylquinoxaline

The ultimately pure red OLED using new electrophosphorescent compound, bis(2,3-diphenylquinoxaline)iridium(acetylace-tonate) [(QH)2 Ir(acac)] is described. Electrophosphorescence peak wavelength and bandwidth were advanced for the purest red color stimulus to 680nm with full width at half maximum of 89nm by doping (QH)2 Ir(acac) into a light emitting electron transport layer composed of 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole. The most vivid red electrophosphorescence with CIE chromaticity coordinates better than x=0.70 and y=0.28, which are the closest to the ultimate limit of pure red among reported OLEDs, was attained and maintained even in luminance brighter than 600cd/m2. A very high maximum external electrophosphorescent quantum efficiency of 10.2% was also realized.