An Efficient Synthesis of Symmetrical Oligothiophenes: Synthesis and Transport Properties of a Soluble Sexithiophene Derivative

We report a new approach for the synthesis of symmetrical oligothiophenes based
on a highly efficient palladium-catalyzed Ullmann coupling reaction. This synthetic route
enables the simple preparation of substituted oligothiophenes with a wider range of
functionalities and in higher yield compared to previously reported syntheses. We
demonstrate our procedure by preparing a novel, highly soluble a,w-disubstituted
sexithiophene. We present the spectroscopic and structural characterization of the
sexithiophene derivative in solution and in solution cast thin films. Thin film transistors
(TFTs) fabricated using solution cast thin films of dibutylphosphonate-a-sexithiophene
(DBP-a-6T) as the p-type semiconducting channel show the utility of this synthetic
approach in the preparation of solution-deposited organic electronic devices.