Effects of PEDOT:PSS Buffer Layer and Cathode in a Device Structure of $ITO/PEDOT:PSS/TPD/Alq_3/Cathode$

$ITO/PEDOT:PSS/TPD/Alq_3/Cathode$ 소자 구조에서 PEDOT:PSS 층과 음전극의 영향

We have investigated the effect of hole-injection buffer layer and cathodes in organic light-emitting diodes u sing poly (3,4-ethylenedioxythiophene) : poly (stylenesulfonate) (PEDOT: PSS) in a device structure of $ITO/PEDOT:PSS/TPD/Alq_3/Cathode$. Polymer PEDOT:PSS buffer layer was made using spin casting method. Current-voltage, luminance-voltage characteristics and efficiency of device were measured at room temperature with a variation of cathode materials. The device with LiF/Al cathode shows an improvement of external quantum efficiency approximately by a factor of ten compared to that of Al cathode only device. Our observation shows that the energy barrier-height in cathode side is important in improving the efficiency of the organic light-emitting diodes.