We demonstrate a strategy for designing high-performance, ambipolar, acene-based field-effect transistor (FET) materials, which is based on the replacement of C-H moieties by nitrogen atoms in oligoacenes. By using this strategy, two organic semiconductors, 6,13-bis(triisopropylsilylethynyl)anthradipyridine (1) and 8,9,10,11-tetrafluoro-6,13-bis(triisopropylsilylethynyl)-1-azapentacene (3), were synthesized and their FET characteristics studied. Both materials exhibit high and balanced hole and electron mobilities, 1 having μ(h) and μ(e) of 0.11 and 0.15 cm(2)/V·s and 3 having μ(h) and μ(e) of 0.08 and 0.09 cm(2)/V·s, respectively. The successful demonstration of high and balanced ambipolar FET properties from nitrogen-containing oligoacenes opens up new opportunities for designing high-performance ambipolar organic semiconductors.

Two new azapentacene derivatives 9,10-dibromo-6,13-bis(triisopropylsilylethynyl)-1-azapentacene (a) and 8,9,10,11-tetrachloro-6,13-bis(triisopropylsilylethynyl)-1-azapentacene (b) were synthesized, and their FET properties were investigated. Compound b exhibits high and balanced ambipolar transport properties, with the hole and electron mobilities reaching up to 0.12 and 0.14 cm(2) V(-1) s(-1), respectively. This work suggests that chlorination to the N-heteropentacene framework is an efficient way for producing high performance ambipolar organic semiconductors.

A force constant model is developed and applied to the vibrations of the hydrogen halide crystals, HBr, HCl, and HF, in their ordered phases. Fundamental frequencies are calculated and compared to those observed by infrared and Raman spectroscopy. It is found that two bending forces, representing electrostatic interactions, are necessary, one of which partially cancels elastic forces for certain modes. Variations of force constants with interatomic distances and comparisons of their values for the three crystals are briefly discussed.Es wird ein Kraftkonstantenmodell entwickelt und auf die Schwingungen der Wasserstoffhalogenkristalle, HBr, HCl und HF in ihren geordneten Phasen angewendet. Die Grundfreqnenzen werden berechnet und mit denen verglichen, die bei Infrarot-und Ramanspektroskopie beobachtet werden. Es wird gefunden, daB zwei Riegekrafte, die die elektrostatischen Wechselwirkungen darstellen, notwendig sind, von denen eine teilweise die elastischen Krafte fur bestimmte Moden kompensiert. Die Anderungen der Kraftkonstanten mit den interatomaren Abstanden und ein Vergleich ihrer Werte fur die drei Kristalle werden kurz diskutiert.