Synthesis and electrical properties of halogen substituted PPV derivatives

Halogen substituted PPV derivatives (PFPV, PCIPV, PBrPV, PIPV) were prepared in film forms from a water soluble precursor route. The properties of these Polymers were studied by UV-visible spectroscopy and electrical conductivity. According phenylene ring was combined from fluorine to iodine, the position of maximum absorption shifts to the longer wavelength. This indicates that the halogen substituents cause a bathochromic shift changing from strong electron withdrawing fluorine to electron releasing iodine. The maximum absorption and absorption edge due to π-π∗ transition of the polyconjugated homopolymers show 400–430nm and 510–530nm, respectively. In the case of copolymers, they show 410–430nm and 520–540nm, respectively. The electrical conductivity values of FeCl3-doped undrawn polymer films are in the range of 10−3−8.2 S/cm and the drawn ones are in the range of 10−1−72 S/cm. As the substituents are changed from fluorine to iodine, the conductivity values slightly increase because of their electronic and steric effect.