High color stability white OLED with an exterior sandwiched color conversion layer

Abstract A sandwiched color conversion layer (CCL) was prepared on the exterior of a blue organic light-emitting diode (BOLED) to achieve white luminescence. Inorganic red aluminate phosphor was used for color conversion. To enhance optical outcoupling, light extraction layers (LELs) of microlens-like SiO2 scattering arrays (SO-LEL) and a roughed-glass diffuser (rG-LEL) were prepared. The addition of an SO-LEL led to a directional radiation of OLED. A light extraction and scattering model for optical transmission through the SO-LEL was developed. However, the rG-LEL caused a slight broadening in the electroluminescence spectrum. The sandwiched CCL had functions of color conversion, scattering, and light extraction. The white OLED with a sandwiched CCL exhibited directional emission and high color stability along with an optical outcoupling enhancement of 39% in power efficiency and 31% in external quantum efficiency.