Novel Thiophene-Phenylene-Thiophene Fused Bislactam-Based Donor-Acceptor Type Conjugate Polymers: Synthesis by Direct Arylation and Properties

Three new donor acceptor copolymers based on thiophene phenylene thiophene fused bislactam and various donors (3,4-dodecylthiophene, 4,4'-didodecyl-2,2'-bithiophene, and ethylenedioxythiophene) were synthesized, characterized, and used in field-effect transistors. Polycondensation was performed using nonactivated thiophene derivatives by employing palladium-catalyzed direct arylation under phosphine-free conditions. This method is superior to traditional cross-coupling polymerization because it requires fewer synthetic operations and does not employ toxic organometallic intermediates. Regioselective polymers can also be generated by using beta-substituted thiophene derivatives. The studied polymers were tested in a bottom gate top contact thin film transistor (OTFT) architecture. The best electronic performance was shown by polymer P3, with enhanced pi-conjugation due to the appearance of intramolecular attractive interactions.