ABSTRACT
New 3,3'-dithioalkyl-2,2'-bithiophene (SBT)-based small molecular and polymeric semiconductors are synthesized by end-capping or copolymerization with dithienothiophen-2-yl units. Single-crystal, molecular orbital computations, and optical/electrochemical data indicate that the SBT core is completely planar, likely via S(alkyl)â¯S(thiophene) intramolecular locks. Therefore, compared to semiconductors based on the conventional 3,3'-dialkyl-2,2'-bithiophene, the resulting SBT systems are planar (torsional angle <1°) and highly π-conjugated. Charge transport is investigated for solution-sheared films in field-effect transistors demonstrating that SBT can enable good semiconducting materials with hole mobilities ranging from ≈0.03 to 1.7 cm2 V-1 s-1 . Transport difference within this family is rationalized by film morphology, as accessed by grazing incidence X-ray diffraction experiments.
ABSTRACT
Three new organic semiconductors with alkyl chain-substituted tetrathienoacene (TTAR) as the central core and both ends capped with thiophene (DT-TTAR), thienothiophene (DTT-TTAR) and dithienothiophene (DDTT-TTAR) have been synthesized and characterized for organic field effect transistor (OFET) applications. A hole mobility of 0.81 cm2 V-1 s-1 was achieved for the DDTT-TTAR film, which represents the highest mobility yet found for a solution-processable p-type TTAR-based small molecular semiconductors.
