Efficient simple structure red phosphorescent organic light emitting devices with narrow band-gap fluorescent host

Using a narrow band-gap fluorescent host material, bis(10-hydroxybenzo[h] quinolinato)beryllium complex, efficient red phosphorescent organic light emitting diodes (PHOLEDs) comprising two layers have been reported. Significantly low driving voltage of 4.5V to reach a luminance of 1000cd∕m2 is reported in this simple structure PHOLEDs. The current and power efficiencies of bilayered red PHOLED are 9.66cd∕A and 6.90lm∕W, respectively, promising for low power display and lighting applications.