PEDT/PSS for efficient hole-injection in hybrid organic light-emitting diodes

Light-emitting diodes have been prepared by depositing three organic layers successively by spin-coat and evaporation techniques. The first layer of P EDT/PSS smoothens the ITO surface, reduces the probability of electrical sh orts and is beneficial for a high overall yield of the operating devices. A bove all, this layer promotes hole-injection as an important parameter for higher efficiencies and prolonged operation life. The second layer of spin- coated dendritic phenylamines (TDAPB) with high glass transition temperatur e modulates the injection of holes into the emitting layer, formed by evapo rated Alq. By comparing characteristics and operation lifetime data of devi ces with and without PEDT/PSS it is shown that the combination of polymeric and monomeric organic layers leads to highly efficient devices, opening ne w ways to modify device architectures. (C) 2000 Published by Elsevier Scien ce S.A. All rights reserved.