Three white organic light‐emitting diodes with blue‐green fluorescent and red phosphorescent dyes

Abstract This paper reports that well‐balanced white emission with three primary colors can be achieved with a simple white organic light‐emitting diode (WOLED) structure of ITO / α‐NPD (50 nm) / α‐NPD: Btp2Ir(acac) (8 wt%, 6 nm) / α‐NPD (5 nm) / BCP (3 nm) / Alq3: C545T (0.5 wt%, 10 nm) / Alq3 (40 nm) / LiF (0.5 nm) / Al (100 nm). The external quantum efficiency of the device reached 3.8% at a current density (luminance) of 4.6 mA/cm2 (310 cd/m2), and the maximal luminance of the device reached 19,000 cd/m2 at 11.5 V. The insignificant blue shift of the emitting color with an increasing current density can be attributed to the narrowing of the exciton formation zone width.