An Imide‐Based Pentacyclic Building Block for n‐Type Organic Semiconductors

Abstract

A new electron-deficient unit with a fused 5-membered heterocyclic ring was developed by replacing a cyclopenta-1,3-diene from electron-rich donor indacenodithiophene (IDT) with a cyclohepta-4,6-diene-1,3-diimde unit. The imide bridge endows dithienylbenzenebisimide (BBI) with a fixed planar configuration and low energy levels for both the highest occupied molecular orbital (HOMO; -6.24 eV) and the lowest unoccupied molecular orbit (LUMO; -2.57 eV). Organic field-effect transistors (OFETs) based on BBI polymers exhibit electron mobility up to 0.34 cm V s , which indicates that the BBI is a promising n-type building block for optoelectronics.

Acceptor–acceptor-type conjugated polymer semiconductors

“…Moreover, it may be necessary to add the cocatalyst CuI together when Pd(PPh 3 ) 4 as the catalyst, such as A2 [27]. Thirdly, microwave reaction is commonly used to improve reactive efficiency as a heating method [42,[57][58][59][60]. It has many advantages over traditional heating methods, such as fast heating speed, high product quality and sensitive reaction.…”

“…To lower the HOMO level, a novel imide-based building block, dithienylbenzodiimide (TBDI), was designed and synthesized by replacing the central thienothiophene in the monomer of X4 with a less electron-rich benzene moiety [42,43]. B10 was synthesized by the Stille coupling polymerization between TBDI and fluorinated thiophene [42,43]. It exhibited a wide E g opt (~2.0 eV) with a low-lying HOMO level of À 5.74 eV.…”

“…The structure of these WAs usually adopts fluorination or introduces the sp 2 -N atom. The substituted F atom on thiophene can effectively form intermolecular interactions, such as the hydrogen bond contacting with CÀH of aromatic ring and the F•••S contact, to improve the flatness of the polymer backbone and the packing order, and thus promoting crystallization [41][42][43][44]. The N atom in thiazole and pyridine can also improve the coplanarity of the main chain, order and crystallization through the N•••S contact and the smaller steric hindrance, and hence the electron mobility (l e ) [27,45,46].…”

Imide‐Functionalized Polymer Semiconductors

“…[84] Jiang and our group independently developed af used diimide electron-deficient unit, dithienylbenzodiimide (TBDI), in which ac entral phenyl ring was fused with two adjacent thiophenesf eaturing imide-containingh eptacyclic rings. [85] When copolymerized with various donor co-units, such as thiophene, bithiophene, difluorobithiophene, as eries of polymer semiconductors, 75, 76,a nd 77,w ere synthesized with low-lying LUMOs in the range of approximately À3.65 to À3.78 eV, [a] Opticalb and gap estimated from the absorptiononset of thin films. [b] Estimated from E HOMO = E LUMO ÀE g opt .…”

Recent structural evolution of lactam- and imide-functionalized polymers applied in organic field-effect transistors and organic solar cells

“…[4][5][6][7] Secondly, constructing acceptor units with strong electron-withdrawing lactam or imide groups provides the molecules and polymers with low-lying energy levels of the lowest unoccupied molecular orbital (LUMO), thus promoting electron injection efficiency and enhancing the device air stability. [8][9][10] Thirdly, a variety of side chains can be substituted on the amide nitrogen atom to adjust the polymer solubility, lm morphology, and the selfassembly of the side chain. [11][12][13] Some functional side chains were also incorporated into polymers to fabricate devices with a specic function.…”