Photoinduced modification of photoluminescent and electroluminescent properties in poly(p-phenylene vinylene) derivative

Abstract

Modification of photoluminescent and electroluminescent properties due to photoirradiation in air of a poly(p-phenylene vinylene) derivative, poly(2-methoxy-5-dodecyloxy-p-phenylene vinylene), and their application to the patterning of the emission from polymer light-emitting device (PLED) are mentioned and discussed. The observed change of the photoluminescence spectrum upon irradiation can be divided into two stages. At the first stage, the photoluminescence intensity rapidly drops to about 40% of initial intensity while the spectrum shape is unchanged. On the other hand, the intensity is unchanged while the spectrum is considerably blue shifted by further irradiation. This result is discussed in terms of photoinduced defect creation and scission of main chain due to photo-oxidation. The emission from the PLED with semitransparent Al cathode drops upon photoirradiation of the device in air and eventually disappears. This indicates that the Al electrode is so thin and the atmospheric oxygen can pass through the Al film and react with the polymer during photoirradiation. The importance of thickness of the Al electrode to the patternability of the device is also mentioned.