Research Project Highlight

Tetrathiafulvalene-Functionalized Thiophene Copolymerized with 3,3″‘-Didodecylquaterthiphene: Synthesis, TTF Trapping Activity, and Response to Trinitrotoluene

ttf 1Solution processable organic semiconductors have been a focus for past few decades for their potential applicability in low-cost electronic devices. Introduction of functionality into the polymeric backbone can influence electrical and optical properties. Our synthetic approach begins with a hydroxymethyl-substituted copolymer consisting of 3,3‴ -didodecyl quaterthiophene (as in PQT12) as repeat unit along with an additional thiophene ring, which enabled other organic functional groups to be grafted such as tetrathiafulvalene (TTF).

ttf 2The TTF side-chain polymer was observed to be active for TNT detection in a manner similar to what we had observed for the small molecule. This demonstrates the new polymer as a vehicle for compatibilizing the often-insoluble TTF with an electron-rich polymer and also shows that the response we reported previously was not due to a special solid-state effect of the small molecule. The blend system of PQT12 with a copolymer gets more uniform distribution of the functional group while still having electrical properties like PQT12. The OFET based on the blend of TTF side-chain polymer and 5wt % PQT12 when exposed to 10−3mg TNT/mL IPA solution, output currents were significantly increased. We also found an unexpected negative Seebeck coefficient for the pristine TTF-modified polymer, which further indicated the strong hole trapping activity of the TTF additive.

Related

Organic semiconductors for use in plastic electronic devices and other alternative active circuits such as display backplanes are generally hole-transporters. It is much more challenging to design electron transporters, which are often needed to complete a circuit or even a single device.

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