The development of new organic semiconductors with improved electrical performance and enhanced environmental stability is the focus of considerable research activity. This communication presents the design, synthesis, and device stability data for novel bis-5'-alkylthiophen-2'yl-2,6-anthracene organic semiconductors. When incorporated into thin-film field-effect transistors, mobilities as high as 0.5 cm2/Vs and on/off current ratios greater than 107 are observed. We have investigated device stability in terms of both shelf life and operating lifetime. Devices incorporating the reported semiconductors display an average field-effect mobility of 0.4 cm2/Vs for DHTAnt and an on/off current ratio of 106 even after 15 months of storage. Furthermore, there is no decrease in performance during continuous operation of the devices over several thousand cycles.

We described here the self-assembling of a three-dimensional array of single-wall nanotubes (SWNTs). The distinctive choice of materials allowed for the self-assembly of SWNTs with low resistance conducting polymer links into a conducting network that when embedded into an insulating host shows no disruption of the conduction path. The ability to control network formation independently of the electrical properties of the host drastically changes the design of these conducting organic networks. Thus, enabling the tailoring of their electrical properties while addressing issues of film processability relevant for their application as printable conductors in organic electronic applications. These networks provide opportunities for applications in micro- and nanoelectronics.

Azobenzene modified polyaramides and several model compounds fitted with atropisomeric 2,2′-binaphthyl linkages exhibit thermo-and photoresponsive chiroptical behavior when evaluated in dilute solution environments. The trans-azobenzene modified polymers were characterized by CD spectra with intense molar ellipticities in the 300-400 nm spectral window. Specific rotation magnitudes at the sodium D-line ranged into the hundreds of degrees and were dependent upon the extent of binaphthyl loading along the polymer chain. The irradiation of the polymer samples to drive the trans f cis isomerization process resulted in an immediate chiroptical response, with CD band intensities and optical rotations significantly diminished. These effects were fully reversible and were attributed to the presence of one-handed helical conformations in the trans-azobenzene modified polymers that were severely disrupted following the trans f cis isomerization reaction.

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Conformationally restricted copolyaramides containing a combination of 4,4′‐azobenzene, 1,4‐phenylene, and chiral 2,2′‐binaphthylene main‐chain segments exhibit photoresponsive chiroptical behavior stemming from multiple trans‐cis‐isomerization reactions triggered within their polymer backbones. In contrast to their more randomly constructed counterparts, copolymer variants endowed with periodic backbone structures undergo reversible, wavelength‐dependent inversions in their optical rotations in response to multiple ultraviolet‐light/visible‐light illumination cycles. Similar behavior is also observed for a smaller oligomer fitted with a periodic arrangement of its monomer units. In their present forms, the periodic constructs constitute a new class of solution‐based, photomodulated chiroptical switches that may be suitable for applications in a number of emerging technological areas. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 566–577, 2004

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