Han Guo1 Yingfeng Wang1 Yongqiang Shi1 Xugang Guo1

1, South University of Science and Technology of China, Shenzhen, , China

Imide-functionalized π-conjugated materials are the most promising semiconductors in organic electronics, attributed to the strong electron-withdrawing capability and good solubilizing ability of imide group. Semiconductors derived from naphthalene diimide (NDI) and perylene diimide (PDI) are the “star materials” in organic thin-film transistors (OTFTs) and polymer solar cell field, showing remarkable device performance. [1] The design and synthesis of novel imide-functionalized arenes with optimized geometry and optoelectronic property has greatly advanced the field of organic electronics.

We report here a series of novel imide-functionalized ladder-type bithiophene imide derivatives (BTIs) with up to 5 imide groups and 15 rings in a row.[2] The homopolymers PBTIs show tunable frontier molecular orbital (FMO) levels and film morphologies.[3] A novel imide-functionalized thiazole unit, 2,2'-bithiazolethienyl-4,4',10,10'-tetracarboxdiimide (DTzTI), was also synthesized, which enables the access of all-acceptor homopolymer PDTzTI.[4] The homopolymers PBTIs and PDTzTI all exhibit favorable unipolar n-type transport behavior in top-gate/bottom-contact OTFTs with highest electron mobilities > 3 cm2 V−1 s−1.[3] Notably, all polymers do not show undesirable kink in transistor curves, thus avoiding mobility overestimation. The lower FMO levels in PDTzTI lead to suppressed Ioff of 10−10-10−11 A, thus remarkable Ion/Ioff of 107-108 is achieved without patterning, while maintaining high μe of 1.6 cm2 V−1 s−1. Besides all-acceptor homopolymers, these novel imide-functionalized arenes are used to construct donor-acceptor polymers, which also show unipolar n-type transport with remarkable electron mobilities > 1 cm2 V1 s1. When used as acceptor materials, the all-polymer solar cells show power conversion efficiencies approaching 7%, the highest value that is not based on NDI or PDI polymer acceptors.[5]

This systematic study represents a remarkable advance in the development of novel imide-functionalized arenes, which enables the access of a series of high-performance unipolar electron transporting materials and offers important guidelines for further invention of n-type semiconductors. When incorporated into OTFTs and all-polymer solar cells, these imide-functionalized polymers show highly promising device performance, corroborating the efficacy of imide groups for enabling high-performance n-type semiconductors.

[1] Guo, X.; Facchetti, A.; Marks, T. J. Chem. Rev. 2014, 114, 8943
[2] Wang, Y.; Guo, H.; Ling, S.; Arrechea-Marcos, I.; Wang, Y.; Navarrete, J. T. L.; Oritz, R. P.; Guo, X. Angew. Chem. Int. Ed. 2017, 56, 9924
[3] Wang, Y.; Guo, H.; Guo, X. manuscript in preparation
[4] Shi, Y.; Guo, H.; Qin, M.; Zhao, J.; Wang, Y.; Wang, H.; Wang, Y.; Facchetti, A.; Lu, X.; Guo, X. submitted
[5] Wang, Y.; Yan, Z.; Guo, H.; Uddin, M. A.; Ling, S.; Zhou, X.; Su, H.; Dai, J.; Woo, H. Y.; Guo, X. Angew. Chem. Int. Ed. 2017, 10.1002/anie.201708421