Spectromicroscopic investigation of polymer light-emitting device degradation

The degradation mechanism of a polymer light-emitting device (PLED) based on poly(3,4-ethylenedioxythiophene) poly(4-styrenesulfonate) (PEDOT:PSS) was investigated by X-ray scanning photoelectron microscopy. Spectromicroscopic analysis of the surface of the emission layer (EML) of the degraded PLED revealed that island-like structures, containing sulfur (S) presumably in sulfide (–C–S–C–) and thiol (–C–S–H) configurations, were generated. The analysis results further suggest that S out-diffused from the PEDOT:PSS layer and formed sulfide and thiol configurations in the EML, and that effective conduction path channels were generated through the island-like structures for current dissipation between the electrodes, resulting in PLED degradation.