Dibenzothiophene derivatives as new prototype semiconductors for organic field-effect transistors

New prototype semiconductor materials based on dibenzothiophene (DBT) derivatives were successfully synthesized by a convergent approach using palladium catalyzed Stille coupling reactions. Thermogravimetric analysis, UV-vis spectra and electrochemistry results indicated these materials had good thermal and photooxidation stability. X-Ray diffraction measurements of the vacuum-evaporated films showed enhanced crystalline order with increasing substrate deposition temperature. The ordered vacuum-evaporated films with charge carrier mobility as high as 7.7 × 10⁻² cm² V⁻¹ s⁻¹ and an on/off ratio of nearly 1 × 10⁷ had been achieved with 3,7-bis(5′-hexyl-thiophen-2′-yl)-dibenzothiophene (3,7-DHTDBTT). These results suggest that the 3,7-substituted DBT system is a good prototype for new type organic semiconductors and will play a more important role in organic semiconductors.