White organic light-emitting device with both phosphorescent and fluorescent emissive layers

This paper reports the fabrication of novel white organic light-emitting device(WOLED) by using a high efficiency blue fluorescent dye N-(4-((E)-2-(6-((E)-4-(diphenylamino)styryl)naphthalen-2-yl)vinyl)phenyl)-N-phenylbenzenamine (N-BDAVBi) and a red phosphoresecent dye bis (1-(phenyl) isoquinoline) iridium (III) acetylanetonate (Ir(piq)_2(acac)). The configuration of the device was ITO/PVK:TPD/CBP: N-BDAVBi /CBP/ BALq: Ir(piq)_2(acac)/BCP/Alq_3/LiF:AL. By adjusting the proportion of the dopants (N-BDAVBi, Ir(piq)_2(acac)) in the light-emitting layer, white light with Commission Internationale de l'Eclairage (CIE) coordinates of (0.35, 0.35) and a maximum luminance of 25350cd/m^2 were obtained at an applied voltage of 22V. The WOLED exhibits maximum external quantum and current efficiency of 6.78% and 12cd/A respectively. By placing an undoped spacer CBP layer between the two light-emitting layers and using BCP as hole blocking layer, the colour stabilization slightly changed when the driving voltage increased from 6 to 22 V.