Two types of the organic light-emitting devices (OLEDs) with different emission structures were prepared using Alq3 (aluminum tris 8-hydroxyquinoline) host material and quinacridone (QD) dopant at the emission layer. One is the OLED device with emission layer consisting of Alq3 host material doped with QD dopant ("codoped OLED"). The another one has a seperated QD dopant film in the Alq3 emission layer ("undoped OLED"). The maximum brightness of the codoped and undoped OLEDs were 3207 cd/m2 and 1570 cd/m2, respectively. The wavelength of the maximum emission peak in the undoped sample was 527 nm and shifted slightly toward longer wavelength with the value of 540 nm for the codoped OLED sample. The maximum luminous efficiency of the undoped OLED was about 1.4 lm/W and increased to 7.0 lm/W for the codoped sample.
We synthesized ZnO nanocrystal colloids adopting sol-gel method using zinc acetate dehydrate as precursor, and prepared ZnO films on glass substrates by a spin-coating technique. The effect of annealing temperature on the structure, optical and electrical properties has been studied. The crystallinity and morphologies were improved by the annealing. All film samples show high transmittance of above 80% in the wavelength ranging from 400nm to 1000nm. A minimum resistivity of 5.5x10-3 cm was obtained for the film annealed at 500oC. The crystallinity, oxygen vacancies, and nanocrystalline boundaries seems likely to be crucial factors for these properties
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