Synthesis of Heptacene and Its Hole-Transfer Property of Stable Thin Films.

Heptacene ( 1 ) was produced through a monoketone precursor ( 2 ), which was prepared starting from 1,2,4,5-tetrabromobenzene through 9 steps in a total yield of 10%. Compound 2 was converted to 1 quantitatively by heating at 202 °C. Heptacene exhibited high thermal stability in the solid state without observable change over two months. To investigate the potential value of 1 as a material for p -type organic field-effect transistors (OFETs), the top-contact OFET devices were fabricated by vacuum-deposition of 1 on a hexamethyldisilazane (HMDS)/SiO 2 /Si substrate. The best performance of hole mobility was 2.2 cm 2 V -1 s -1 . This is the first report that stable heptacene was used in an effective device and examined on its charge carrier property.