Halogens as trace compounds in polymeric light-emitting diodes

We investigated the elemental composition of different layers of polymeric light-emitting diode (pLED) model structures. Of special concern have been poly-(3,4-ethylenedioxythiophene) (PEDOT)/polystyrenesulfonate (PSS) and po ly-phenylenevinylene (PPV) films, which are used widely in pLEDs. We found halogen compounds as impurities: bromine in the PEDOT/PSS and chlorine in t he PPV layer. It is argued that the presence of halogen containing compound s could be an important reason for the degradation of pLEDs. (C) 2000 Elsev ier Science S.A. All rights reserved.