Remarkable enhancement of efficiencies for red, green, and blue tandem phosphorescent organic light-emitting diodes by utilizing a non-doped photovoltaic-type charge generation unit

摘要

We have achieved a remarkable enhancement in current efficiencies and power efficiencies for red, green, and blue tandem phosphorescent organic LEDs (T-PhOLEDs) by employing LiF/Al/fullerene/zinc-phthalocyanine/MoO3 as a charge generation unit (CGU). Fullerene/zincphthalocyanine with a proper absorption property in the visible region can absorb a part of photons from emission layers within T-PhOLEDs, which facilitates the charge generation and separation within CGU. At the identical luminance of 1,000 cd m(-2), the current efficiencies for red, green, and blue T-PhOLEDs are 3.3-, 2.1-, and 2.9-fold those of the corresponding single-unit devices, and power efficiencies are increased by 72.2%, 13.6%, and 37.2%, respectively. (C) 2019 The Japan Society of Applied Physics