Imide-functionalized π-conjugated materials are highly promising semiconductors in organic electronics. Semiconductors derived from naphthalene diimide (NDI) and perylene diimide (PDI) are the “benchmark materials” in organic thin-film transistor (OTFT) and all-polymer solar cell (all-PSC) field, showing remarkable device performance. The design and synthesis of novel imide-functionalized arenes with optimized geometry and opto-electronic 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. The homopolymers PBTIs show tunable frontier molecular orbital (FMO) levels and film morphologies. 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. The homopolymers PBTIs and PDTzTI all exhibit unipolar n-type transport in OTFTs with highest electron mobilities (μes) &gt; 3 cm2 V−1 s−1. Notably, all polymers do not show undesirable kink in transistor curves, thus avoiding mobility overestimation. The deep FMOs of PDTzTI lead to suppressed Ioffs of 10−10-10−11 A, thus remarkable Ion/Ioffs of 107-108 are achieved without semiconductor 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 copolymers, which also show unipolar n-type transport with substantial μes &gt; 1 cm2 V−1 s−1. When used as acceptor materials, the all-PSCs exhibit power conversion efficiencies of ~9%, the highest value not based on NDI or PDI polymer acceptors. This systematic study represents a great advance in the development of imide-functionalized arenes, which enable the access of a series of high-performance unipolar electron transporting materials and offer important guidelines for further invention of n-type semiconductors. When incorporated into OTFTs and all-PSCs, these imide-functionalized polymers show highly promising device performance, corroborating the efficacy of imide groups for enabling high-performance n-type organic semiconductors.

Imide-functionalized n-type polymers for high-performance organic thin-film transistors and all-polymer solar cells

256th National Meeting (2018)

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