A highly color-stability white organic light-emitting diode by color conversion within hole injection layer

We demonstrated a novel-structure white organic light-emitting devices (WOLEDs) composed of a greenish blue fluorescent emitting layer and a red fluorescent dye-doped hole injection layer. The spectra of WOLEDs show no change at a wide range current density operation and long-term continuous operation. We concluded that carriers recombined inside the emitting layer in the WOLEDs to produce a greenish blue electroluminescence (EL), and a part of the EL was absorbed by the red fluorescent guest doped hole injection layer and converted into red photoluminescence (PL); the whole white emission from the device was a mixture of the greenish blue EL and red PL.