Study of Nanostructured Polymeric Composites and Hybrid Layers Used for Light-Emitting Diodes

Nanocomposite polymeric thin films of poly(2-methoxy-5-(2'-ethyl hexyloxy)phenylene vinylene) (MEH-PPV) with nano-crystalline titanium oxide (nc-TiO2) and polycarbazole (PVK) with cadmium selenide (CdSe) were fabricated by spin-coating. A 20-nm-thick nanocrystalline (molybdenum oxide) MoO3 layer prepared by using thermal oxidation was also spin-coated with a PVK film. A study of photoluminescence (PL) spectra of the polymers and nanocomposites showed an enhancement in the photoluminescence from the nanocomposites. Moreover, MEH-PPV+nc-TiO2 composites exhibited a blue-shift of the PL spectrum as compared to that of the polymer film. The current-voltage characteristics of the Mo/nc-MoO3/PVK/Al-Au structures show that a semitransparent metallic coating or a transparent polymer can serve as a cathode in devices with enhanced charge carrier injection.