A series of novel monomers and polymers containing aromatic-donor and o-quinoid-acceptor units was prepared, and the relationship between their spectral and electrochemical properties and their structures was investigated. X-ray structure analyses of the monomers possessing thiophene units revealed coplanar conformations, whereas calculations of the monomers containing N-methylpyrrole showed torsional conformations. Cyclic voltammetry showed amphoteric properties for all the monomers and p- and n-doping processes for most of the polymers. The reduction potentials were primarily dependent on the electron-accepting character of the o-quinoid-acceptor units. The electrochemical behavior of the polymers was characterized by cyclic voltammetry and suggested narrow-bandgap systems. The bandgaps determined from optical absorption spectra range from 0.5 to 1.4 eV. The polymer composed of thiophenes and benzo[1,2-c;3,4-c‘]bis[1,2,5]thiadiazole exhibited the narrowest bandgap.

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Novel pi-electron systems with trifluoromethylphenyl groups and/or a thiazolothiazole unit were developed as n-type semiconductors for OFETs. They showed excellent n-type performances with high electron mobilities. The trifluoromethylphenyl group was found to be very effective in inducing n-type behavior. The thiazolothiazole unit was favorable for forming stacking structures leading to efficient intermolecular pi-pi interactions.

Novel thiazole oligomers and thiazole/thiophene co-oligomers with trifluoromethylphenyl groups were developed as n-type semiconductors for OFETs. They showed excellent n-type performances with high electron mobilities. A 5,5'-bithiazole with trifluoromethylphenyl groups forms a closely packed two-dimensional columnar structure leading to a high performance n-type FET. The electron mobility was enhanced to 1.83 cm2/Vs on the OTS-treated substrate.

Although electrically stimulated neurite outgrowth on bioelectronic devices is a promising means of nerve regeneration, immunogenic scar formation can insulate electrodes from targeted cells and tissues, thereby reducing the lifetime of the device. Ideally, an electrode material capable of electrically interfacing with neurons selectively and efficiently would be integrated without being recognized by the immune system and minimize its response. Here we develop a cell membrane-mimicking conducting polymer possessing several attractive features. This polymer displays high resistance towards nonspecific enzyme/cell binding and recognizes targeted cells specifically to allow intimate electrical communication over long periods of time. Its low electrical impedance relays electrical signals efficiently. This material is capable to integrate biochemical and electrical stimulation to promote neural cellular behaviour. Neurite outgrowth is enhanced greatly on this new conducting polymer; in addition, electrically stimulated secretion of proteins from primary Schwann cells can also occur on it.

The advantages of organic field-effect transistors (OFETs), such as low cost, flexibility and large-area fabrication, have recently attracted much attention due to their electronic applications. Practical transistors require high mobility, large on/off ratio, low threshold voltage and high stability. Development of new organic semiconductors is key to achieving these parameters. Recently, organic semiconductors have been synthesized showing comparable mobilities to amorphous-silicon-based FETs. These materials make OFETs more attractive and their applications have been attempted. New organic semiconductors resulting in high-performance FET devices are described here and the relationship between transistor characteristics and chemical structure is discussed.

Supporting InformationGeneral. Melting points were obtained on a Yanaco melting point apparatus and uncorrected. EI mass spectra were collected on a SHIMADZU GCMS-QP5000 mass spectrometer. UV-vis spectra were recorded on a SHIMADZU Multi Spec-150.Emission spectra were collected on a SHIMADZU RF-1500 spectrometer. The calorimetric data were obtained on a Seiko Exter-5000 at a scanning rate 10 °C min -1 .Differential pulse voltammogram was recorded on a BAS-100B system containing terabutylammoniumhexafluorophoshate ( TBAPF 6 ) ( 0.1moldm -3 in dry THF ). The Pt disk, Pt wire and SCE were used as the working, counter, and reference electrodes, respectively.

Aromatic ring-condensed TTF derivatives exhibited excellent p-type FET performances in thin films. Introduction of fused benzene and pyrazine rings to the TTF skeleton was effective to enhance the intermolecular interactions and stability to oxygen. Ordered molecular alignment was confirmed by XRD studies. A pi-stacking structure was observed in the single crystal of diquinoxalinoTTF.