Random vs. alternating donor-acceptor copolymers: A comparative study of absorption and field effect mobility

Neubig, Anne; Thelakkat, Mukundan

doi:10.1016/j.polymer.2014.04.004

Cited by 10 publications

(8 citation statements)

References 30 publications

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“…The functional groups for polymerization were chosen to be bromines, not only in order to keep the synthesis route as short as possible but also mostly as it can be employed in many different polymerization techniques that are commonly used to synthesize state-of-the-art low-bandgap polymers, such as Stille, Suzuki, Yamamoto, Negishi, Kumada, and Heck cross-coupling polymerizations. It has also been shown earlier that no strictly alternating donor–acceptor sequence is required for lowering the optical gap and random or statistical copolymerization is a viable option. , When the azide-functionalized comonomer 5 is added in small quantities (less than 5 wt %) to AA/BB-type polycondensations, a cross-linkable tercopolymer can be obtained that exhibits repeating units y which are identical to the regular strictly alternating copolymer and a repeating unit x consisting of the azido-functionalized thiophene 5 and the comonomer carrying the complementary functional groups.…”

Section: Resultsmentioning

confidence: 99%

Azido-Functionalized Thiophene as a Versatile Building Block To Cross-Link Low-Bandgap Polymers

et al. 2016

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We unveil a concept for the design of crosslinkable semiconducting polymers that is based on a modular tercopolymerization which stands out by its low synthetic effort, easy accessibility, and its broad range of applications. 3-(6-Azidohexyl)thiophene was used as a comonomer in the synthesis of a variety of low-bandgap copolymers using different polymerization techniques such as Suzuki−Miyaura cross-coupling and Stille cross-coupling. We show that when only a small amount (5−10 mol %) of azide groups is introduced into the polymers, the impact on absorption and electrochemical properties (HOMO/LUMO values) is negligible. The small amount of azide functionality is however enough to obtain polymers that can easily be cross-linked by UV illumination. Thermal stability of the solid state packing and alignment is studied in neat polymer thin films as well as in blends with [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 70 BM) as a relevant model blend system. Solvent resistivity of these polymer films is investigated by absorption and photoluminescence measurements. It is finally shown in organic field effect transistors that the introduction of 10% azide-functionalized monomer does not considerably influence hole transport mobility (0.20−0.45 cm 2 V −1 s −1 ).

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Section: Resultsmentioning

confidence: 99%

Azido-Functionalized Thiophene as a Versatile Building Block To Cross-Link Low-Bandgap Polymers

et al. 2016

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“…Organic photovoltaics (OPV) offer a promise of low-cost, large area, and flexible electronic devices through the use of conjugated polymer active layers. , The backbones of conjugated polymers have been extensively investigated, yielding a broad range of linkage patterns, including homopolymers, random, − alternating, and block copolymers. , Explicit design choices within these major architectures, such as identity of donor/acceptor monomers , and side-chain engineering, allow for precise tuning of desirable properties such as absorption breadth, frontier orbital levels, solubility, and polymer self-organization. Of the previously mentioned backbone architectures, a perfectly alternating donor–acceptor polymer structure is broadly popular for achieving low band gaps and improved efficiencies in solar cells. ,, However, many of these systems exhibit red-shifted absorption, sacrificing short-wavelength photons. , More recently, a new class of semi-random polymers have successfully incorporated multiple, distinct, and randomized chromophores that exhibit broadened absorption profiles. − Semi-random polymers based on regioregular poly(3-hexylthiophene) (rr-P3HT) have additional unique design advantages.…”

Section: Introductionmentioning

confidence: 99%

“…Organic photovoltaics (OPV) offer a promise of low-cost, large area, and flexible electronic devices through the use of conjugated polymer active layers. 1,2 The backbones of conjugated polymers have been extensively investigated, yielding a broad range of linkage patterns, including homopolymers, random, 3−7 alternating, 8 and block copolymers. 9,10 Explicit design choices within these major architectures, such as identity of donor/acceptor monomers 11,12 and side-chain engineering, 13 allow for precise tuning of desirable properties such as absorption breadth, frontier orbital levels, solubility, and polymer self-organization.…”

Section: ■ Introductionmentioning

confidence: 99%

Investigation of Random Copolymer Analogues of a Semi-Random Conjugated Polymer Incorporating Thieno[3,4-b]pyrazine

et al. 2016

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Semi-random conjugated polymers based on 3-hexylthiophene have been extensively investigated within the past several years as an effective route to broadening absorption without losing desirable properties of poly(3-hexylthiophene) (P3HT). Here, we closely investigate the structural, optical, and electronic differences found in randomized analogues of poly(3-hexylthiophene–thiophene–2,3-dimethylthieno[3,4-b]pyrazine) (P3HTT-TP) semi-random polymers. Proton nuclear Overhauser effect spectroscopy is used to identify linkages within the conjugated backbone, and UV–vis, cyclic voltammetry, and grazing incidence X-ray diffraction are used to determine the influence of the subtle differences in monomer connectivities. Semi-random P3HTT-TP was found to have a stronger intramolecular charge transfer absorption band and higher thermal transitions compared to its randomized analogue. Additionally, the function of the thiophene unit in the semi-random polymers is observed and demonstrated to have key electronic effects as well as maintaining a higher HOMO level, aside from providing needed stoichiometric balance to the acceptor monomer. This work demonstrates the utility of the semi-random polymer approach as a robust tool for incorporating small amount of electron-poor monomers for the purpose of improving the absorption breadth of P3HT-based polymers.

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“…All the polymers exhibit typically dual band absorption: the higher-energy bands are attributed to π−π* transition, while the low-energy bands correspond to intramolecular charge transfer (ICT) arising from the interactions between donor and acceptor moieties. 38 In chloroform solution, PD-CST owns the low-energy absorption band in a range of ca. 500−800 nm, whereas PD-3F-CST, PD-23F-CST, and PD-25F-CST show similar absorption behavior with the low-energy absorption band in a range of ca.…”

Section: ■ Results and Discussionmentioning

confidence: 96%

“…The UV–vis–NIR absorption spectra of the CST -based polymers were recorded both in dilute CHCl 3 solution and as thin films spin-coated on quartz glass (Figure ). All the polymers exhibit typically dual band absorption: the higher-energy bands are attributed to π–π* transition, while the low-energy bands correspond to intramolecular charge transfer (ICT) arising from the interactions between donor and acceptor moieties . In chloroform solution, PD-CST owns the low-energy absorption band in a range of ca.…”

Section: Resultsmentioning

confidence: 99%

Cyanostyrylthiophene-Based Ambipolar Conjugated Polymers: Synthesis, Properties, and Analyses of Backbone Fluorination Effect

et al. 2018

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Herein, we report the synthesis and characterization of a series of ambipolar cyanostyrylthiophene (CST)-based conjugated polymers without or with fluorine substituents, namely PD-CST, PD-3F-CST, PD-23F-CST, and PD-25F-CST. With the change of the number or incorporating position of fluorine substitutes on the novel CST unit, the electron mobilities of field-effect transistors based on these polymers dramatically increased from 0.0015 cm2 V–1 s–1 for PD-CST, 0.13 cm2 V–1 s–1 for PD-3F-CST, and 0.25 cm2 V–1 s–1 for PD-23F-CST to 0.53 cm2 V–1 s–1 for PD-25F-CST. AFM and GIXRD investigation indicated that the annealed PD-25F-CST thin film possesses stronger crystallization tendency and highly ordered lamellar packing than those of the other polymers. Further theoretical calculations and single-crystal X-ray diffraction analysis deeply revealed the remarkable influences of the number and incorporating position of fluorine substitutes on the frontier orbital energy levels, backbone conformation, and charge transport properties of polymer semiconductors.

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Random vs. alternating donor-acceptor copolymers: A comparative study of absorption and field effect mobility

Cited by 10 publications

References 30 publications

Azido-Functionalized Thiophene as a Versatile Building Block To Cross-Link Low-Bandgap Polymers

Azido-Functionalized Thiophene as a Versatile Building Block To Cross-Link Low-Bandgap Polymers

Investigation of Random Copolymer Analogues of a Semi-Random Conjugated Polymer Incorporating Thieno[3,4-b]pyrazine

Cyanostyrylthiophene-Based Ambipolar Conjugated Polymers: Synthesis, Properties, and Analyses of Backbone Fluorination Effect

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