Solution Processable Pseudo n-Thienoacenes via Intramolecular S···S Lock for High Performance Organic Field Effect Transistors

New solution processable 3,5-dithioalkyl dithienothiophene (DSDTT) based small molecular semiconductors end functionalized with various (fused) thiophenes including dithienothiophene (DTT), thienothiophene (TT), and thiophene (T) are synthesized and characterized in organic field effect transistors (OFETs). The new DSDTT core was synthesized via a one-pot [1 + 1 + 1] methodology. For comparison, non-thiolated 3,5-dialkyl dithienothiophene (DRDTT) based molecules are also prepared and characterized. Optical, electrochemical, and computed electronic structures of these molecules are investigated and contrasted. Single crystal data support evidence of S(alkyl)···S(thiophene) intramolecular locks, with a very short intramolecular S–S distance of 3.17 Å, planarizing the structure as for the equivalent extended n -thienoacenes. Via a solution-shearing semiconductor film deposition method, these semiconductors exhibit a OFET hole mobility up to 2.6 cm 2 V –1 s –1, the greatest reported to date for fused/all-thiophene based small molecular organic semiconductors.