Highly oriented polyarylenevinylene thin films

Oriented thin films of poly(2,5-dimethoxy-p-phenylenevinylene) (MO-PPV) and poly(2,5-thienylenevinylene) (PTV) were prepared. Methoxy-pendant precursors of MO-PPV and PTV, which are soluble in organic solvents and stable at around room temperature, were prepared. The precursors were spin-coated on polymer substrates, and were allowed to convert partially under well-defined conversion conditions. Then, polymer substrates were stretched at around 100°C under the flow of dry HCl gas which acted as catalyst for full conversion of precursors. Highly oriented thin films with the thickness of about 0.1 μm were obtained. Optical absorption spectra of oriented films exhibited large anisotropy which proved the alignment of π-conjugated chains. Also the shifts of π-π^* peaks to longer wavelength evidenced the increase of average π-conjugated length in oriented chains.