Effects of the mixing ratio of the CaAl12O19:mn and Zn2SiO4:mn color-conversion layer on the color tunable emissions of white organic light-emitting devices.

ABSTRACT

The optical properties of white organic light-emitting devices (WOLEDs) fabricated utilizing a CaAl12O19Mn and Zn2SiO4Mn phosphor layer were investigated. X-ray diffraction patterns for CaAl12O19Mn and Zn2SiO4Mn phosphors showed that Mn ions in the CaAl12O19Mn phosphors were completely substituted into Ca ions and that Mn ions in the Zn2SiO4Mn phosphors were completely substituted into Zn ions. Field emission scanning electron microscopy images showed that the size of the CaAl12O19Mn phosphor was approximately between 0.1 and 3 microm, and that the size of the Zn2SiO4Mn phosphor was smaller than 7 microm. The color coordinates of the electroluminescence spectra for WOLEDs with phosphor thicknesses of 0.25 and 0.35 mm shifted to the white emission side because the generated blue light from the blue OLEDs combined with the red and green lights was converted by the CaAl12O19Mn and the Zn2SiO4Mn phosphor down-conversion layers.