Photophysical studies and photovoltaic devices on a low bandgap, high charge-carrier-mobility Poly(Thienylene
Vinylene) (PTV), prepared from a soluble precursor polymer synthesised via the 'dithiocarbamate route', are reported.
In composites with an electron acceptor ([6,6]-phenyl C61- butyric acid methyl ester (PCBM), a soluble fullerene
derivative) photoinduced absorption (PIA) characteristic for charged excitations together with photoluminescence (PL)
quenching are observed indicating photoinduced electron transfer. The "bulk heterojunction" photovoltaic devices using
PTV and PCBM composites show short circuit currents up to 4 mA/cm2 under AM 1.5 white-light illumination. The
photocurrent spectrum of the photovoltaic device shows an onset at about 1.65 eV (750 nm) which corresponds to the
absorption spectrum of the polymer.
A new precursor route towards conjugated polymers is presented. Whereas difficulties occurred for the preparation of poly(2,5-thienylene vinylene) (PTV) derivatives via the existing precursor routes, PTV has been synthesised via a new developed "dithiocarbamate route" in good yields and satisfactory molecular weight. Structural characterisations of the conjugated polymers reveal an optical band gap around 1.7 eV. Organic field effect transistors and organic based photovoltaic devices were made and the results are discussed. Solar cells were produced using a blend of the precursor polymer and PCBM at various ratios. The conversion of the precursor polymer towards the conjugated polymer was performed in situ in film spin-coated from the blend. Promising energy conversion efficiencies were observed which were still improved by thermal annealing of the device at 70°C.