Spectroscopic properties of PEDOTEHIITN, a novel soluble low band-gap conjugated polymer

Polymers with narrow band gap are expected to posses appreciably high RT conductivities, luminescence in the NIR and improved solar energy harvesting properties. Here we report the spectroscopic properties of a soluble and environmentally stable copolymer (PEDOTEHIITN) with a band-gap of ca. 1.1 eV. The combination of this outstandingly narrow band gap, processability and stability are promising for future electronic and optoelectronic applications.

Photoexcitations In Carbazolyl Substituted Polydiacetylene (pda) Fullerene Composites

It is well known that many non-degenerate ground state conjugated polymers like PPV derivatives show an ultrafast electron transfer to fullerenes upon photoexcitation. In this work we investigate the photoexcited states of fullerene - carbazolyl substituted PDA composites and compare them to the pristine components. We report the finding of photoexcited spins as well as charges in one asymmetric carbazolyl substituted PDA, the CPDO (poly(1-N-carbazolyl-penta-1,3-diyne-5-ol)). While PIA FTIR measurements show strong IRAV bands for this material, LESR studies on the same samples reveal photoexcited spins. Although CPDO samples show a dark ESR signal, which is well known for the topochemical polymerization, photoexcitation studies clearly reveal, that the LESR does not come from photoinduced polymerization. No enhancement of LESR signal is found for mixtures of CPDO and fullerenes, in our case a special solubilized fullerene, PCBM. We conclude therefore, that even PDA which show photoexcited charges and spins, do not exhibit a photoexcited charge transfer to fullerenes.

Nano-morphology characterization of organic bulk heterojunctions based on mono and bis-adduct fullerenes

We have studied organic bulk heterojunction photovoltaic devices based on a bridged-bithiophene donor-acceptor type low-band gap polymer blended with PCBM and bis-PCBM. The impact of the molecular arrangement is discussed in terms of the correlation between the solar-cell performance and the degree of crystallization. Differential scanning calorimetry (DSC) and grazing-incidence X-ray diffraction (GIXRD) prove that films with bis-PCBM typically result in more amorphous blends than comparable films with PCBM. Electron tomography (ET) is used to visualize the three dimensional morphology of photoactive layers, confirming the presence of nanofibers, formed in different scales through the thickness in the blended films with mono and bis-fullerenes. (C) 2012 Elsevier B.V. All rights reserve