Fused-ring Pyrrole Organic Semiconductors for Organic Field Effect Transistors

Mihaela S.jpg

Friday, April 9th 2021 at 3:30 PM in Hand 1100

Abstract:  The smallest S, N-heteroacene, thieno[3,2-b]pyrrole is a good building block for organic semiconductors due to the high electron density, asymmetry, and easily modifiable NH group.  Our group have shown that organic semiconductors from thieno[3,2-b]pyrrole display “nearly-ideal” OFET characteristics without compromising charge carrier mobilities or threshold voltages. We have varied the structure and topology to investigate the relatively under-explored banana shape thieno[3,2-b]pyrrole ole semiconductors and the influence of the heteroatom.

Banana shaped donor-acceptor molecules with benzothiadiazole, fluorinated benzothiadiazole acceptors and thieno[3,2-b]pyrrole donor  (TP-BT2T-BT and TP-FBT2T-TP) have been reported by our group and the OFET parameters were evaluated in a bottom-gate/bottom-contact (BGBC) OFET architecture. Hole mobility of 0.08 cm² V^-1 s^-1 was measured for the molecule (TP-BT2T-BT) with benzothiadiazole as the acceptor. The molecule containing fluorinated benzothiadiazole (TP-FBT2T-BT) showed hole mobility of 1.57×10^-3 cm² V^-1 s^-1.

Lengthening conjugation by synthesizing conjugated polymers was employed to facilitate the hole transport and to obtain comparatively stable semiconductors. Our group reported the donor-acceptor polymer containing thienopyrrole donor and diketopyrrolopyroole acceptor, P(DPP-TP) and the OFET parameters were evaluated with bottom-gate/top-contact (BGTC) OFET architecture. An increase in hole mobility to 0.12 cm² V^-1 s^-1 was observed for the polymer (P(DPP-TP)) as compared to the conjugated small molecules.