Blue-shifting the Optical Properties of PPVs by Fluorinating Vinylene Units:Interplay Between Supramolecular-organization and Optical Properties of MEH-PPDFV

摘要

This study is an investigation on the interplay among supramolecular organization and optical properties of thin films of the poly[2-(2-ethylhexyloxy)-5-methoxy]-l,4-phenylenedifluorovinylene (MEH-PPDFV) conjugated polymer, which has fluorinated vinylene units. This interplay is elucidated exploiting atomic force microscopy, spectroscopy ellipsometry, photoluminescence and electroluminescence. Thin films of MEH-PPDFV have been deposited by drop casting on indium-tin-oxide (ITO), quartz and glass substrates. The dependence of polymer chains self-organization and morphology on substrate surface is presented. Furthermore, it is demonstrated that the presence of F-atoms in the vinylene units of the MEH-PPDFV yields a blue optical band gap with the maximum of the fundamental HOMO-LUMO transition at 331nm and photoluminescence at 458nm. A stable blue-greenish electroluminescence is also achieved at 504nm.