White Organic Light Emitting Diodes using Red and Blue Phosphorescent Materials with Blocking Layer

Abstract

High-efficiency white organic light-emitting diodes (WOLEDs) were fabricated with two emissive layers and an blocking layer was sandwiched between two phosphorescent dopants, bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (FIrpic) as the blue emission and a newly synthesized red phosphorescent material guest, bis(5-acetyl-2-phenylpyridinato-N,C2') acetylacetonate ((acppy)2Ir(acac)). This blocking layer prevented a T-T annihilation in a red emissive layer, and balanced with blue and red emission as blocking of hole carriers. The white device showed Commission Internationale d’Eclairage (CIEx,y) coordinates of (0.317, 0.425) at 22400 cd/m2, a maximum luminance of 27300 cd/m2 at 268 mA/cm2, a maximum luminous efficiency and power efficiency of 26.9 cd/A and 18.6 lm/W.