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The distributions of carriers in white organic light-emitting devices can be tuned effectively by incorporating a mixed interface layer, consisting of 4,7-diphenyl-1,10-phenanthroline doped in N,N′-dicarbazolyl-4-4′-biphenyl. By adjusting the thickness and the BPhen concentration of the mixed interface, the optimal devices exhibit maximum current and power efficiencies of 20.9 cd/A and 19.9 lm/W, respectively, and slightly modified Commission Internationale De L’Eclairage coordinates, from (0.3174 0.3276) to (0.3141 0.3218). This is attributed to the good distributions of carriers between two emissive layers by inserting the mixed interface, thereby improving both the exciton formation probability and the charge transport balance. [ABSTRACT FROM AUTHOR]

The performance of white organic light-emitting devices has been improved significantly by incorporating a mixed-transition layer, consisting of the hole-transporting (or electron-transporting) layer doped with the emissive dye. These devices exhibit maximum current and power efficiencies of 13.3 cd/A and 11.3 lm/W, respectively (1.6 and 2 times higher than the corresponding values of devices without the mixed-transition layer), with slightly modified Commission Internationale De L’Eclairage coordinates, from (0.300, 0.371) to (0.312, 0.366). This is attributed to the enhancement of carrier transport by doping, thereby improving both the exciton formation probability and the charge transport balance. [ABSTRACT FROM AUTHOR]

We report the electrical properties of a single conducting polyaniline nanotube measured by a standard four-terminal technique. Camphor sulfonic acid doped polyaniline nanotubes were self-assembled by a template-free method. The directly measured conductivity of the single polyaniline nanotube is very high (∼31.4 S/cm), and its temperature dependence follows the three-dimensional variable range hopping model. However, the bulk conductivity of the polyaniline nanotube pellets is much smaller than the nanotube itself (only 3.5×10[sup -2] S/cm) and ln ρ(T) is linear in T[sup -1/2], which is due to the large intertubular contact resistance. These results will help us to understand the conduction mechanism in conducting polymers. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]