Under a white ambient light illumination and without bias, the color-cathode organic light emitting device (OLED) shows the various reflection colors to display the information by utilizing the internal interference cavity inside rear cathode. In this report, we employed a high conductivity metal-organic material, tris(8hydroxyquinolinato)aluminum (Alq3) doped with Ag nanoparticles, to be the interlayer of this interference cavity cathode. Its good conductivity is leading to a comparable electrical performance with that of reference device. There is a small increase of driving voltage 0.5V at 100 mA/cm2 for colorcathode OLED. In addition, the thicknesses of this interlayer inside this interference cavity varies to 40, 60, 80 and 100 nm to alter the reflection colors such as orange, purple, blue and green.