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Semifluorinated, amorphous polyarylenes PmmpF4 with kinked backbone structure were prepared from a meta-substituted, biphenol-based monomer with varying alkoxy substituents R and 1,2,4,5-tetrafluorobenzene (pF4) via direct arylation polymerization (DAP). The chemistry employed is simple, scalable and does not rely on tedious purification techniques. Polycondensation occurs cleanly without major side reactions. Despite the clean polycondensation reaction, very high molar mass materials are difficult to obtain, which is ascribed to an unusual solubility behavior compared to non-fluorinated analogs, and similar, yet more linear tetrafluorobenzene copolymers based on fluorene or carbazole. In order to investigate this phenomenon further, the side chain-dependent properties PmmpF4 are investigated using linear, branched and cyclic side-chains. While the glass transition temperature of PmmpF4 is a strong function of R and can be varied between 35 °C and 197 °C for constant backbone structure and molecular weight, solubility cannot be improved by using longer linear or branched side chains. Density functional theory calculations suggest significant polarization-type non-covalent interactions between tetrafluorobenzene and the biphenol-based monomer as origin for the observed limited solubility, which guide the design of both kinked and straight conjugated polymers with high molar mass and solubility.

The synthesis, characterization and solar cell performance of PCDTBT and its highly soluble analogue hexyl-PCDTBT with cross-conjugated benzoyl moieties at the carbazole comonomer are presented. Through the use of both model reactions and time-controlled microwave-assisted Suzuki polycondensation, the base-induced cleavage of the benzoyl group from the polymer backbone has been successfully suppressed. Compared to the commonly used symmetrically branched alkyl motif, the benzoyl substituent lowers the energy levels of PCDTBT as well as the band gap, and consequently increases energy of the charge transfer state in blends with PC71BM. As a result, photovoltaic diodes with high-open circuit voltage of above 1 V are realized.

Herein, we report the chain-growth tin-free room temperature polymerization method to synthesize n-type perylene diimide-dithiophene-based conjugated polymers (PPDIT2s) suitable for solar cell and transistor applications. The palladium/electron-rich tri-tert-butylphosphine catalyst is effective to enable the chain-growth polymerization of anion-radical monomer Br-TPDIT-Br/Zn to PPDIT2 with a molecular weight up to Mw ≈ 50 kg mol−1 and moderate polydispersity. This is the second example of the polymerization of unusual anion-radical aromatic complexes formed in a reaction of active Zn and electron-deficient diimide-based aryl halides. As such, the discovered polymerization method is not a specific reactivity feature of the naphthalene-diimide derivatives but is rather a general polymerization tool. This is an important finding, given the significantly higher maximum external quantum efficiency that can be reached with PDI-based copolymers (32–45%) in all-polymer solar cells compared to NDI-based materials (15–30%). Our studies revealed that PPDIT2 synthesized by the new method and the previously published polymer prepared by step-growth Stille polycondensation show similar electron mobility and all-polymer solar cell performance. At the same time, the polymerization reported herein has several technological advantages as it proceeds relatively fast at room temperature and does not involve toxic tin-based compounds. Because several chain-growth polymerization reactions are well-suited for the preparation of well-defined multi-functional polymer architectures, the next target is to explore the utility of the discovered polymerization in the synthesis of end-functionalized polymers and block copolymers. Such materials would be helpful to improve the nanoscale morphology of polymer blends in all-polymer solar cells.

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Two novel star-like cyclam derivatives with appended four amino groups and four PEG-arms have been synthesized. The complex formation of cyclam and the cyclam derivatives and with Cu(II) has been studied by UV-Vis and time-resolved laser-induced fluorescence (TRLFS) measurements. The cyclam ligands investigated form 1:1 complexes with Cu(II). Rapid complex formation was found for cyclam and the pegylated derivative. By way of contrast, complete attainment of complexation between Cu(II) and cyclam ligand having external primary amino groups needs approx. 1 hour. By TRLFS measurements a quench effect of the Cu(II) on the fluorescence of the ligand was found. This behaviour was used to determine the complex formation between Cu(II) and the ligands.