Study of the interface effects of a free-grown polypyrrole layer in PPVOLEDs

One of the major concerns in the OLED area is the operating lifetime of the devices. It is well known that the insertion of a conductive polymeric lay er between the ITO and the active layer reduces the degradation effects and thus increases the operating lifetime of the OLEDs. In this work we study the effect of a free-grown insulating polypyrrole (PPY) layer in the thresh old voltage and I-V characteristics of the devices consisting of ITO, PPV a nd aluminum when we insert the polypyrrole layer between the PPV layer and either one of the electrodes.