Dialkoxybithiazole: A New Building Block for Head-to-Head Polymer Semiconductors

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• 作者：Xugang Guo ; Jordan Quinn ; Zhihua Chen ; Hakan Usta ; Yan Zheng ; Yu Xia ; Jonathan W. Hennek ; Roc铆o Ponce Ortiz ; Tobin J. Marks ; Antonio Facchetti
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：February 6, 2013
• 年：2013
• 卷：135
• 期：5
• 页码：1986-1996
• 全文大小：514K
• 年卷期：v.135,no.5(February 6, 2013)
• ISSN：1520-5126

文摘

Polymer semiconductors have received great attention for organic electronics due to the low fabrication cost offered by solution-based printing techniques. To enable the desired solubility/processability and carrier mobility, polymers are functionalized with hydrocarbon chains by strategically manipulating the alkylation patterns. Note that head-to-head (HH) linkages have traditionally been avoided because the induced backbone torsion leads to poor 蟺鈥撓€ overlap and amorphous film microstructures, and hence to low carrier mobilities. We report here the synthesis of a new building block for HH linkages, 4,4鈥?dialkoxy-5,5鈥?bithiazole (BTzOR), and its incorporation into polymers for high performance organic thin-film transistors. The small oxygen van der Waals radius and intramolecular S(thiazolyl)路路路O(alkoxy) attraction promote HH macromolecular architectures with extensive 蟺-conjugation, low bandgaps (1.40鈥?.63 eV), and high crystallinity. In comparison to previously reported 3,3鈥?dialkoxy-2,2鈥?bithiophene (BTOR), BTzOR is a promising building block in view of thiazole geometric and electronic properties: (a) replacing (thiophene)C鈥揌 with (thiazole)N reduces steric encumbrance in 鈥揃TzOR鈥揂r鈥?/b> dyads by eliminating repulsive C鈥揌路路路H鈥揅 interactions with neighboring arene units, thereby enhancing 蟺鈥撓€ overlap and film crystallinity; and (b) thiazole electron-deficiency compensates alkoxy electron-donating characteristics, thereby lowering the BTzOR polymer HOMO versus that of the BTOR analogues. Thus, the new BTzOR polymers show substantial hole mobilities (0.06鈥?.25 cm²/(V s)) in organic thin-film transistors, as well as enhanced I_on:I_off ratios and greater ambient stability than the BTOR analogues. These geometric and electronic properties make BTzOR a promising building block for new classes of polymer semiconductors, and the synthetic route to BTzOR reported here should be adaptable to many other bithiazole-based building blocks.