Single Crystal Field Effect Transistor of a Y-Shaped Ladder-Type Oligomer

We report herein the X-ray single crystal structural analysis, density functional theory calculations, and electrical characteristics in single crystal field effect transistor configuration of the Y-shaped ladder-type oligomer 15,16-dithia-5,10-diazanaphtho[2,3-alpha]benzo[c]anthracene. The molecule is quasiplanar, crystallizes in the monoclinic P 2 1 / c space group with four molecules in the unit cell and forms stacks along the b direction with intermolecular distances of 3.83 Å. Vapor phase transport crystal growth yielded large plate-shaped shiny purple crystals more than 2 cm long which allowed for construction of single crystal FET. Room temperature linear mobility of 0.05 cm 2 /V was obtained. The transfer characteristics of the device within the temperature range of 250−295 K were also measured. The activation energy for carrier detrapping was found to be 540 meV, much higher than most other oligoacene crystals known to date. This is probably due to the relatively large separation between molecules along the c axis of the crystal.