Two-color-mixed white organic light-emitting diodes with a high color temperature

Efficient two-color-mixed white organic light-emitting diodes are presented herein by employing a sky-blue phosphorescent dopant of iridium(III)bis[4,6-(difluorophenyl)-pyridinato-N,C 2′]picolinate (FIrpic) and an orange phosphorescent dopant of bis(2-phenylquinoline)(acetylacetonate)iridium(III) (Ir(phq)2acac) on the emissive layer. Very stable color variation under Δ 0.02 until a 5000 cd/m2 brightness value was realized by efficient carrier control in a multi-stacked emitting layer of blue/red/blue colors. Maximum current and power efficiencies of 23.8 cd/A and 22.9 lm/W in the forward direction were obtained. With balanced emission from the two emitters, the white-light emission of high correlated color temperature of 7308 K and the Commission Internationale de I'Eclairage coordinates of (0.30, 0.33) were achieved.