White organic light-emitting devices with a solution-processed and molecular host-employed emission layer

The brightness, efficiency, chromaticity, and processibility of white organic light-emitting devices have been markedly improved by forming therein via spin-coating a single white emission layer, in which the red, green, and blue dyes of iridium-based complexes were previously solution-mixed into the host matrix composed of small molecules instead of polymers. Among the hosts studied, the 4,4(')-bis(carbazol-9-yl)-biphenyl-based devices performed best in terms of luminance and efficiency for having the lowest-energy barrier for electrons to inject from the hole-blocking layer to the host layer. The device having a pure white emission of (0.34, 0.35) had a maximum power efficiency of 2.9 lm/W at an applicable luminance of 1680 cd/m(2), while 5.6 lm/W at 550 cd/m(2) for that of (0.34, 0.39). (c) 2005 American Institute of Physics.