Characteristics of metal-poly(phenylene vinylene) interfaces

摘要

Abstract: The progress of thermal conversion of the thin films of poly(p-xylylene- $alpha@-tetrahydrosulfonium chloride) to poly(phenylene vinylene) (PPV) was investigated in situ under ultra-high vacuum by x-ray photoelectron spectroscopy (XPS). We found that at 150 - 200$DGR@C chlorine was completely eliminated, sulfur was less than 1%, oxygen was 10 - 15% and carbon was about 85 - 90%. One could reduce the oxygen content to 3 - 5% by heating the samples at 320$DGR@C. The interfaces of Ca or Al with the PPV films were then investigated using XPS. The interaction between Ca and PPV was very weak. Band bending of the Ca/PPV interface was very slow indicating the formation of Schottky barrier was a slow process. In contrast, Schottky barrier formation of Al/PPV was much faster. The slow barrier formation at the metal-PPV interface may be due to the shielding by the surface oxygen impurities, part of which underwent metal oxide formation at the interface. Our results may be highly relevant to the application of sulfonium precursor derived PPVs in optoelectronic layer devices where the interface chemistry is likely to govern the device performance.!23