A highly efficient,transparent and stable charge generation unit based on a p-doped monolayer

We demonstrate a highly efficient, transparent and stable charge generation unit (CGU) combining a p-doped hole transporting layer (HTL) with an electron extraction layer (EEL). The CGU exhibits high optical transparency of over 90% and good stability with little voltage variation under stress. We propose a working mechanism of CGU based on an investigation of the CGU-only devices excluding the influences of emitters. Holes and electrons are generated in the p-doped layer, while the EEL facilitates electron injection into the adjacent electron transporting layer. It is expected that this CGU is a promising candidate for easy-fabrication, low-power-consumption and high-stability tandem white OLED for future display and lighting application.