Combinatorial fabrication and studies of bright white organic light-emitting devices based on emission from rubrene-doped 4,4′-bis(2,2′-diphenylvinyl)-1,1′-biphenyl

Abstract

Very bright and efficient white multilayer organic light-emitting devices based on orange-emitting 2–10-nm-thick layers of 0.25 and 0.5 wt % rubrene-doped 4,4^′-bis(2,2^′-diphenylvinyl)-1,1^′biphenyl are described. The color coordinates of all but one of the devices are well within the white region at 6–12 V, corresponding to a dynamic white brightness range of 30 dB. Their highest brightness $L_{\max }$ was over $\text{74\hspace{0.05em}000\hspace{0.17em}}{\mathrm{Cd/m}}^2;$ in all devices $L_{\max }$ exceeded $\text{50\hspace{0.05em}000\hspace{0.17em}}{\mathrm{Cd/m}}^2.$ The maximum efficiencies were 11.0 Cd/A, 6.0 lm/W, and 4.6% at 5.8 V, $\text{0.6\hspace{0.17em}}{\mathrm{mA/cm}}^2,$ and $\text{68\hspace{0.17em}}{\mathrm{Cd/m}}^2$ in the 0.25 wt %, 2-nm-thick doped layer device. The color variation is attributed to either emission from different zones in devices with a thin doped layer, or saturation of emission sites due to relatively light doping.