Synthesis, Characterization, and Field‐Effect Transistor Performance of Thieno[3,2‐b]thieno[2′,3′:4,5]thieno[2,3‐d]thiophene Derivatives

The synthesis, characterization, and field‐effect transistor (FET) properties of a new class of thieno[3,2‐b]thieno[2′,3′:4,5]thieno[2,3‐d]thiophene derivatives are described. The optical spectra of their films show the presence of stronger interactions between molecules in the solid state. Thermal analyses reveal that the three materials are thermally stable and have no phase transitions at low temperature. The crystal structures are determined, and show π‐stacked structures and intermolecular S···S contacts. These organic materials exhibit p‐type FET behavior with hole mobilities as high as 0.14 cm 2 V −1 s −1 and an on/off current ratio of 10 6 . These results indicate that thieno[3,2‐b]thieno [2′,3′:4,5]thieno[2,3‐d]thiophene, as a linear π‐conjugated system, is an effective building block for developing high‐performance organic semiconductors.