Diketopyrrolopyrrole (DPP)-based copolymers have received considerable attention as promising semiconducting materials for high-performance organic thin-film transistors (OTFTs). However, these polymers typically exhibit p-type or ambipolar charge-transporting characteristics in OTFTs due to their high-lying highest occupied molecular orbital (HOMO) energy levels. In this work, a new series of DPP-based n-type polymers have been developed by incorporating fused bithiophene imide oligomers (BTIn) into DPP polymers. The resulting copolymers BTIn-DPP show narrow band gaps as low as 1.27 eV and gradually down-shifted frontier molecular orbital energy levels upon the increment of imide group number. Benefiting from the coplanar backbone conformation, well-delocalized π-system, and favorable polymer chain packing, the optimal polymer in the series shows promising n-type charge transport with an electron mobility up to 0.48 cm2 V−1 s−1 in OTFTs, which is among the highest values for the DPP-based n-type polymers reported to date. The results demonstrate that incorporating fused bithiophene imide oligomers into polymers can serve as a promising strategy for constructing high-performance n-type polymeric semiconductors.
Bibliographical noteFunding Information:
Y.Z., L.T., and H.S. contributed equally to this work. S.Z. acknowledges the financial support from the National Key R&D Program of ?Strategic Advanced Electronic Materials? (2016YFB0401100) and the National Natural Science Foundation of China (61574077), as well as the Major Program of Natural Science Foundation of the Higher Education Institutions of Jiangsu Province, China (No.19KJA460005). X.G. is grateful to the National Natural Science Foundation of China (51573076) and Shenzhen Basic Research Fund (JYJ20170817105905899). H.S. acknowledges the National Natural Science Foundation of China (21801124). The authors thank Dr. Yinhua Yang at Materials Characterization and Preparation Center, Southern University of Science and Technology (SUSTech) for the NMR characterization. The work was also supported by Center for Computational Science and Engineering of SUSTech.
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- bithiophene imide
- n-type polymer semiconductors
- organic thin-film transistors
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Materials Chemistry