Siloxane Side-Chain-Modified Diketopyrrolopyrrole and Thienopyrrole Containing Small Molecules for Organic Field-Effect Transistors

• Published in: ACS applied electronic materials 2022-11, Vol.4 (11), p.5340-5350
• Main Authors: Udamulle Gedara, Chinthaka M., Ma, Ziyuan, Talukder, Md Muktadir, Gunawardhana, Ruwan, Biewer, Michael C., Stefan, Mihaela C.
• Format: Article
• Language: English
• ISSN: 2637-6113; 2637-6113
• DOI: 10.1021/acsaelm.2c01033

Thieno­[3,2-b]­pyrrole (TP) is a donor moiety employed in organic semiconducting small molecules and polymers. Among the TP-containing small molecules reported, benzo­[c]­[1,2,5]­thiadiazole (BT) acceptor-based donor–acceptor (DA) type molecules have shown mobilities of ∼0.1 cm2 V–1 s–1. In this study, we are reporting the synthesis, characterization, and testing of the organic field-effect transistor (OFET) performance of two donor–acceptor–donor (DAD) type small molecules with TP donors and siloxane-functionalized diketopyrrolopyrrole (DPP) acceptors, namely, diethyl 2,2′-((2,5-bis­(6-(1,1,1,3,5,5,5-heptamethyl­trisiloxan-3-yl)­hexyl)-3,6-dioxo-2,3,5,6-tetrahydropyrrolo­[3,4-c]­pyrrole-1,4-diyl)­bis­(thiophene-5,2-diyl))­bis­(4-methyl-4H-thieno­[3,2-b]­pyrrole-5-carboxylate (DPP-2T-2TP) and diethyl 2,2′-((2,5-bis­(6-(1,1,1,3,5,5,5-heptamethyl­trisiloxan-3-yl)­hexyl)-3,6-dioxo-2,3,5,6 tetrahydropyrrolo­[3,4-c]­pyrrole-1,4-diyl)­bis­(furan-5,2-diyl))­bis­(4-methyl-4H-thieno­[3,2-b]­pyrrole-5-carboxylate (DPP-2F-2TP). The difference between DPP-2T-2TP and DPP-2F-2TP is the spacer between the donor and acceptor. According to a few reports, siloxane-containing side chains were known to provide stability in ambient conditions in OFETs compared to their alkyl-substituted analogs. In this study, siloxane side-chain-substituted small molecular OFETs were fabricated, annealed, and tested under ambient conditions. Both molecules showed OFET activity with a maximum hole mobility of 4.10 × 10–2 cm2 V–1 s–1 (DPP-2T-2TP) and 6.40 × 10–5 (DPP-2F-2TP) cm2 V–1 s–1 in ambient conditions, where thiophene spacer containing DPP-2T-2TP had a better performance.