Abstract
We have investigated effect of thickness dependence of characteristics in PVCz based two-layered polymer light emitting diodes(ITO/HTL/EML/Mg-Ag). Device structure was PVCz:Cz/PVCz:Pe. We have clarified fundamental current transport and electroluminescent characteristics in the two-layered PVCz polymer LED's that have emission and hole transport layers separately. It was elucidated that high luminance polymer LED's with a luminance higher than 10000cd/m^2 was realized for the first time by the PVCz based two-layered structure.