Synthesis of thieno[3,4-c] pyrrole-4,6-dione-based small molecules for application in organic thin-film transistors

The synthesis of two alternating donor-acceptor (D-A) small molecules revolving around thieno[3,4-c]pyrrole-4,6-dione (TPD) as the main acceptor building block is reported herein. The materials are synthesized using a robust Stille coupling to attach the TPD core with thiophene donors on either of its side, and completed with an aldol condensation under mild conditions for the addition of terminal secondary acceptor building blocks, representing a sought out A2-D-A1-D-A2 structure. The two newly synthesized materials are set to be used as organic semiconductors in organic thin-film transistor (OTFT) devices. Comparative optical, computational, and electrochemical studies were carried out on these new materials to investigate their ability to act as potential n-type organic semiconductors. The materials were then incorporated into bottom-gate bottom-contact OTFT devices, and subsequent thin-film engineering studies were done to probe the effects that solvent and post-deposition annealing conditions had on device performance. From these conditions, the rhodanine-derived D-A material exhibited the greatest electron field-effect mobility (0.011 cm2 V−1 s−1), and a threshold voltage of 20.1 V under vacuum.