Extended isoindigo core: synthesis and applications as solution-processable n-OFET materials in ambient conditions

Xu, Shiliang; Ai, Na; Zheng, Jie; Zhao, Na; Lan, Zhenggang; Wen, Li‐Rong; Wang, Xiao; Pei, Jian; Wan, Xin

doi:10.1039/c4ra14072a

Cited by 27 publications

(18 citation statements)

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“…[7][8][9] In particular, ambipolar materials, which enable hole and electron transport, are very important to realize singlecomponent organic logic circuits 10,11 and light-emitting transistors 12,13 as well as the basic understanding of carriertransport behavior in the solid state. [16][17][18][19][20][21] Among the building blocks constituting organic semiconductors, isoindigo (II) is well known as an electron-decient unit realizing a high performance OFET. 14,15 However, the ambipolar properties of small molecules are still lower than those of polymer semiconductors.…”

Section: Introductionmentioning

confidence: 99%

Design and structure–property relationship of benzothienoisoindigo in organic field effect transistors

2015

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A novel planar p-conjugated small molecule, benzothienoisoindigo (BTII), in which additional benzene rings are fused with the thieoisoindigo (TII) unit, has been designed and synthesized. We report the impact of the planar p-framework and p-conjugation length on the carrier transport properties using three sets of molecules, BTII, isoindigo (II) and TII, bearing the same hexyl-side chain. The absorption spectra are remarkably red-shifted in the order of II < TII < BTII along with the enhanced molar extinction coefficient in the low-energy region, leading to the reduced bandgap. The single-crystal structure analyses revealed that all molecules have a planar backbone, and II and BTII are packed into a slipped columnar structure showing highly one-dimensional p-p interactions, while TII did not form, any noticeable intermolecular overlaps. The carrier transport properties were investigated in field-effect transistors (FETs). All molecules exhibited typical ambipolar properties. Among them, BTII showed the highest FET p-dominant ambipolar performance with the hole mobility of 0.095 cm 2 V À1 s À1 and electron mobility of 5.8 Â 10 À3 cm 2 V À1 s À1 on the tetratetracontane (TTC)-modified substrate and p-type performance with the hole mobility of 0.18 cm 2 V À1 s À1 on the octadecyltrimethoxysilane (OTMS)-modified substrate. The microstructure of thin films was characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements.These results indicated that smooth and densely packed nanorod-like crystalline grains are formed by extension of the p-conjugation in BTII. Due to the p-extension of planar organic semiconductors, the novel BTII unit can be extended for the rational design of high performance FET materials. † Electronic supplementary information (ESI) available: Additional information on material synthesis, thermal properties, X-ray single crystal structure analysis, and fabrication and characterization of organic eld-effect transistors. CCDC 1061785-1061787. For ESI and crystallographic data in CIF or other electronic format see

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Section: Introductionmentioning

confidence: 99%

Design and structure–property relationship of benzothienoisoindigo in organic field effect transistors

2015

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“…[ 117 ] Small molecule M22 that further fused phenyl rings to M21 was also synthesized. [ 118 ] Yue and co‐workers extended the conjugation length by fusing TT to isoindigo. [ 28 ] The resulting M23 showed slight red‐shift and significant enhanced of molar extinction coefficient.…”

Section: Modification Strategies Of Isoindigo‐derived Polymer For Ofetsmentioning

confidence: 99%

Semiconducting Polymers Based on Isoindigo and Its Derivatives: Synthetic Tactics, Structural Modifications, and Applications

Wei

Zhang

2021

Adv Funct Materials

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(1 of 33)benzothiadiazole (BT), [8,9] naphthalene diimide (NDI), [10,11] and isoindigo. [12][13][14] Isoindigo is an isomer of the wellknown industrial dye indigo and can be directly isolated from nature. [15,16] The structural difference between isoindigo and indigo is the relative positions of the nitrogen atom and the carbonyl group. In the indigo molecule, the nitrogen atoms are not connected to the carbonyl groups. Moreover, the nitrogen atoms in isoindigo molecule are connected with carbonyl groups. In 2012, indigo was reported as the active layer material of organic fieldeffect transistors (OFETs), which exhibited well-balanced ambipolar transport. [17] However, the H-bonded indigo showed extremely low solubility. For achieving good solution processibility, solubilizing side chains are introduced on the nitrogen atoms, which on the other hand break the intramolecular hydrogen bond, thereby reducing the molecular conjugation and limiting the electronics applications. [18] By contrast, the side chains on isoindigo do not break the hydrogen bond, and thus isoindigo is considered as a superior building block for organic electronic materials. [18,19] Since isoindigo was first used in organic electronics in 2010, [20] isoindigo-derived conjugated polymers have attracted considerable attention and have been developed rapidly due to the strong electron deficiency and high molecular planarity of isoindigo unit. [12,21] Moreover, compared with DPP, BT or NDI, isoindigo has a π-framework that can be readily modified. The structural feature of isoindigo endows itself many modification sites, including the side chains attached to the lactam nitrogen atoms, the center double bond, and the phenyl rings. More than twenty isoindigo derivatives have been reported. [22][23][24][25][26][27][28] Based on isoindigo and its derivatives, various isoindigo-derived conjugated polymers have been synthesized and many of them showed excellent performance. For example, using isoindigo-derived conjugated polymers, the hole and electron mobilities of p-and n-type OFETs have reached 14.4 and 14.9 cm 2 V −1 s −1 , respectively, and some ambipolar OFETs exhibited high hole/electron mobilities of up to 5.97/7.07 cm 2 V −1 s −1 . [29][30][31] The power conversion efficiencies (PCEs) of fullerene-containing organic photovoltaics (OPVs) and all-polymer solar cells (all-PSCs) based on isoindigo-derived polymers have exceeded 10% and 7%, respectively. [32,33] Furthermore, various structural modification

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“…14 Further extension of the π-conjugated system (benzothiophene-fused isoindigo and benzofuran-fused isoindigo, Scheme 1c and d) led to small molecular OFETs with electron mobility up to 0.074 cm 2 V −1 s −1 under ambient conditions. 15 More recently, similar modifications on the isoindigo core were also reported (Scheme 1e-g) including thieno [3,2-b]thiophene isoindigo, 16 benzothienoisoindigo, 17 and thieno [3,2-b]- [1]benzothiophene isoindigo. 18 OFET devices fabricated with small molecules and polymers based on these structures all showed promising performances.…”

Section: Introductionmentioning

confidence: 99%

Thiophene-fused isoindigo based conjugated polymers for ambipolar organic field-effect transistors

Zhao

Cai

et al. 2016

Polym. Chem.

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A series of donor-acceptor (D-A) type conjugated polymers based on novel thiophene-fused isoindigo (TII) were designed and synthesized via palladium catalyzed Stille copolymerization. We found that the redesign of the synthesis of brominated TII was necessary, and the α-bromination had to be completed at the very beginning, or β-brominated TII was obtained, which only led to cross conjugated polymers.Once the bromination was introduced at the correct position, fully conjugated D-A type polymers could be obtained. A series of fully conjugated polymers were obtained by Stille coupling polymerization of α-brominated TII with different donors, and among them, copolymers with thiophene (T) and (E)-1,2-bis (3-octylthiophen-2-yl)ethene (TVT-8) showed acceptable solubility and were suitable to fabricate solution-processable organic field-effect transistors (OFETs). Top-gate/bottom-contact (TG/BC) devices were constructed for the polymers to test their OFET performances. Both fully conjugated polymers exhibit two-orders of magnitude higher charge carrier mobilities than the cross conjugated ones, and PTII-T shows balanced electron and hole mobilities and PTII-TVT-8 is a p-type dominated semiconductor. These observations indicated that the developed TII unit that has improved coplanarity can be a promising building block for the construction of highly efficient conjugated polymers for OFET applications.

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Extended isoindigo core: synthesis and applications as solution-processable n-OFET materials in ambient conditions

Abstract: Two isoindigo derivatives fused with benzothiophene (C20-DBTII) and benzofuran (C20-DBFII) heterocycles have been synthesized.

Cited by 27 publications

References 27 publications

Design and structure–property relationship of benzothienoisoindigo in organic field effect transistors

Design and structure–property relationship of benzothienoisoindigo in organic field effect transistors

Semiconducting Polymers Based on Isoindigo and Its Derivatives: Synthetic Tactics, Structural Modifications, and Applications

Thiophene-fused isoindigo based conjugated polymers for ambipolar organic field-effect transistors

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