S. Li et al., In situ XPS study of the interactions of evaporated copper atoms with poly(p-phenylene vinylene) and its ring-substituted derivatives, SURF SCI, 454, 2000, pp. 990-994
Angle-resolved X-ray photoelectron spectroscopy was employed for the in sit
u study of the interactions between thermally evaporated copper atoms and c
onjugated electroluminescent polymer, such as poly(p-phenylene vinylene) an
d its soluble derivative, poly [2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenyle
ne vinylene] (MEH-PPV). Quantitative changes in the C 1s and Cu 2p core-lev
el spectra, the Cu LMM Auger line shapes, and the chemical stoichiometries
of polymer-metal interfaces with progressive deposition of the copper atoms
were carefully monitored. Chemical interactions had occurred between each
polymer and the copper atoms, resulting in the formation of an interfacial
layer of metal complexes. There appeared to be no significant migration of
bulk absorbed oxygen to the polymer surface upon copper deposition unlike t
hat observed during the deposition of metals of lower work function. Diffus
ion of Cu atoms into the near-surface region of the polymer was observed fo
r PPV and MEH-PPV films. The interactions of the Cu atoms with the polymer
surfaces were also compared with the results obtained for the Al/PPV and Al
/MEH-PPV interfaces. (C) 2000 Elsevier Science B.V. All rights reserved.