Synthesis of dithienogermole-containing polythiophenes

- New dithienogermole-containing polythiophenes were prepared by the Stille-coupling reactions.
- Optical and electrochemical properties of the dithienogermole-containing polythiophenes were investigated.
- The TFT activities of these polythiophene films were investigated, showing how the germole units affect the TFT activity.

Alternating copolymers composed of dithienogermole and thiophene, bithiophene, and dithienosilole (pDTG2-T, pDTG2-2T, and pDTG2-DTS2) were prepared by the Stille coupling reactions of dibromodithienogermole and the respective distannylthiophene derivatives. Examination of their electronic states with respect to their UV-vis absorption spectra and cyclic voltammograms (CVs) revealed enhanced conjugation in the order of pDTG2-T < pDTG2-2T < pDTG2-DTS2. However, the interchain π-π interaction of the polythiophenes in the film state was enhanced in the opposite order. The highest organic thin film transistor (OTFT) mobility was obtained for pDTG2-2T, indicating that the intermolecular π-π interaction affected the OTFT activity of the films more significantly than the intramolecular π-conjugation in these polythiophenes.

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