ORGANIC AND INORGANIC ELECTROLUMINESCENT DISPLAYS INCLUDING A POROUS SILICON LAYER

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We investigated on electrical and optical properties in organic EL display devices including inorganic porous silicon layer in order for the improvement of efficiency and color quality. Research results are summarized as follows.1.We controlled band-gap energy of porous silicon in the range between 1.6 and 2.3eV by adjusting preparation conditions such as anodization current density and light irradiation metode. We found that the porous silicon has great advantage of hole -blocking to the carrier transport process through the organic layer when is used as a buffer layer for PVK based polymer EL devices.2.We proposed new device structure consisting of polymer emissive layer, fluorescent guest dopant and porous silicon layer, and showed the deep blue, bright green and pure white electroluminescence by designing the structure and materials. The external quantum efficiencies and color coordinates (x, y) are 5.1%' (0.15,0.09), 5.5% (0.20,0.60) and 4.0% (0.33,0.33) in blue, green and white OLEDs, respectively.3.Optical analysis was developed for the stacked layer organic EL devices on the basis of fresnel analysis and transferred matrix. By employing this program, new color panel structure named "Side-coupling color conversion method" was first proposed and showed a possibility to increase the white efficiency twice as much by utilizing a lateral emission. High efficiency beyond the theoretical limitation of transition probability was confirmedIn conclusion, efficiency of the device was significantly improved by this study, but technical problems are still remained in reliability of the device, efficiency of red OLED and reproducibility of porous silicon for the practical viewpoints.