Electromigration of the conducting polymer in organic semiconductor devices and its stabilization by cross-linking

X-ray photoelectron spectroscopy (XPS) measurement of the ratio of poly(3,4-ethylenedioxythiophene) (PEDT) to polystyrenesulfonate (PSS) reveals accumulation of PEDT+ at the interface between the PEDT:PSSH hole-injection layer and the organic semiconductor during diode operation. This ionic drift of PEDT+ occurs even at low fields of 1 V cm(-1), which will have an impact on the operational stability of the characteristics of organic light-emitting diodes. XPS and Raman spectroscopy indicate that dedoping of PEDT+ does not occur significantly in hole-only devices. Cross-linking at the 1 mol % level can stabilize the conducting polymer sufficiently against electromigration. (C) 2007 American Institute of Physics.