Composites made by mixing porous silicon grains with poly(p phenylene vinyl
ene) or PPV were studied by optical and electrical characterization. Infrar
ed, UV-vis absorption, Raman and photoluminescence measurements were perfor
med on films with different silicon concentrations and the results were com
pared to those obtained separately from porous and PPV samples. The optical
spectra showed that porous silicon was incorporated into the polymer witho
ut significant change in the polymer structure. In contrast, porous silicon
was oxidized and aged by the conversion process of the polymer. Light emit
ting diodes fabricated with the composites have low turn-on voltage as comp
ared to devices using PPV. The improvement was explained by the enhancement
of the conductivity and by the increase in the contact area between the fi
lm and the electrode due to the change in morphology of the surface of the
film. (C) 2000 Elsevier Science S.A. All rights reserved.