Highly efficient tandem blue phosphorescent organic LEDs with external quantum efficiency exceeding 42%

Abstract

High-performance tandem blue phosphorescent organic LEDs (T-BPhOLEDs) are important for solid-state lighting and flat-panel display. Herein, we have realized a highly efficient T-BPhOLED by using the photovoltaic-type charge generation unit (CGU) of LiF/Al/fullerene/zinc-phthalocyanine/MoO3, blue phosphorescent emitter of bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III) and electron transporter of 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene. The charge generation ability of CGU could be enhanced by the photovoltaic function of fullerene/zinc-phthalocyanine in T-BPhOLEDs. Under high luminance, a cycle composed of the CGU and emission layers in T-BPhOLEDs could convert some of the internal radiation into external radiation for improving performance. Simultaneously, the optimal T-BPhOLED exhibits a high external quantum efficiency of 42.9% at 100 cd·m−2.