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

作者：Guo, Xugang; Quinn, Jordan; Chen, Zhihua; Usta, Hakan; Zheng, Yan; Xia, Yu; Hennek, Jonathan W.; Ortiz, Rocio Ponce; Marks, Tobin J.^*; Facchetti, Antonio

来源：Journal of the American Chemical Society, 2013, 135(5): 1986-1996.

DOI：10.1021/ja3120532

• THIN-FILM TRANSISTORS
• FIELD-EFFECT TRANSISTORS
• STRUCTURE-PROPERTY RELATIONSHIPS
• HIGH-PERFORMANCE
• HIGH-MOBILITY
• CHARGE-TRANSPORT
• POLYTHIOPHENE SEMICONDUCTORS
• AMBIPOLAR SEMICONDUCTORS
• CONJUGATED POLYMERS
• DEVICE PERFORMANCE

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 pi-pi 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'-dialkoxy-5,5'-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)center dot center dot center dot O(alkoxy) attraction promote HH macromolecular architectures with extensive pi-conjugation, low bandgaps (1.40-1.63 eV), and high crystallinity. In comparison to previously reported 3,3'-dialkoxy-2,2'-bithiophene (BTOR), BTzOR is a promising building block in view of thiazole geometric and electronic properties: (a) replacing (thiophene)C-H with (thiazole)N reduces steric encumbrance in -BTzOR-Ar- dyads by eliminating repulsive C-H center dot center dot center dot H-C interactions with neighboring arene units, thereby enhancing pi-pi 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 (0.06-0.25 cm(2)/(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.

• 出版日期2013-2-6
• 单位南方科技大学; 西北大学