Bright white small molecular organic light-emitting devices based on a red-emitting guest–host layer and blue-emitting 4,4′-bis(2,2′-diphenylvinyl)-1,1′-biphenyl

Bright multilayer white organic light-emitting devices (OLEDs) based on red-emitting [2-methyl-6-[2-∼(2,3,6,7-tetrahydro-1H, 5H-benzo [ij] quinolizin-9-yl)-ethenyl]-4H-pyran4-ylidene] propane-dinitrile (DCM2)-doped ${\mathrm{N,N}}^{\prime }-{\mathrm{diphenyl-N,N}}^{\prime }-\mathrm{bis(1-naphthylphenyl}{\text{)-1,1}}^{\prime }-$ $\mathrm{biphenyl}{\text{-4,4}}^{\prime }-\mathrm{diamine}$ (α-NPD) and blue-emitting ${\text{4,4}}^{\prime }-\mathrm{bis}{\text{(2,2}}^{\prime }-\mathrm{diphenylvinyl}{\text{)-1,1}}^{\prime }-\mathrm{biphenyl}$ (DPVBi) are described. The blue emission increased relative to the red emission with increasing bias, but the color coordinates of the total emission were well within the white region at $\text{V>10\hspace{0.17em}}\mathrm{V}.$ The most lightly doped device, which contained a 5 nm thick layer of 0.5 wt. % of the dye dopant, exhibited the highest power efficiency, $\text{4.1\hspace{0.17em}}\mathrm{lm/W},$ external quantum efficiency of $\text{3.0\%,}$ and white brightness $L_{\max }\text{>50\hspace{0.05em}000\hspace{0.17em}}{\mathrm{Cd/m}}^2$ (at ∼1100 mA/cm²).