The change in the interface of conjugated polymer/nano-particle composite with aluminum electrode has been studied. From the X-ray photoelectron spectroscopic studies, it was revealed that there was no significant difference of interfacial reaction between poly(p-phenylenevinylene) (PPV) and PPV/SiO2 nano-composite films. However, interfacial reaction of PPV/SiO2 nano-composite film with Al was saturated promptly because of more residues, as compared with that of PPV. Enhancement of current density by nano-particles has been observed, and it could be understood by morphology effect on field strength at the film-electrode interface that PPV/SiO2 nano-composite film shows rougher surface than that of PPV film. The change in the effective thickness of the film induced by the thickness variation of the film due to surface morphology effects on the distribution of effective field strength applied to the films. (C) 2004 Elsevier B.V. All rights reserved.