Blue top-emitting organic light-emitting devices using a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline outcoupling layer

We fabricate a blue top-emitting organic light-emitting device (TEOLED) based on 4,4′-bis(2,2′-diphenylvinyl)-1,1′-biphenyl. Different from the conventional TEOLEDs that use ITO as a thickness adjustment layer to make the cavity length matchable with the resonant wavelength of the blue light, we construct the blue emission TEOLED through suppressing multiple-beam interference and utilizing wide-angle interference to enhance the blue emission. With a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline light outcoupling layer to reduce the reflectivity of the Sm/Ag cathode, the blue emission can be obtained and its chromaticity is comparative to that from a bottom-emitting OLED. In addition, the blue emission shows stable spectra when the viewing angle alters from 0° to 75°.