Thieno[3,4-b]thiophene–benzo[1,2-b:4,5-b′]dithiophene-based polymers bearing optically pure 2-ethylhexyl pendants: Synthesis and application in polymer solar cells

Ikai, Tomoyuki; Kojima, Ryotaro; Katori, Sinji; Yamamoto, Tomoko; Maeda, Katsuhiro; Takahashi, Kohshin; Kanoh, Shigeyoshi

doi:10.1016/j.polymer.2014.11.033

Cited by 14 publications

(10 citation statements)

References 53 publications

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“…However, in rare cases as recently demonstrated by Percec and co‐workers, homochiral dye‐based crystals may also assemble as supramolecular helices that disregard chirality upon mesophase formation . These results may accordingly relate to homochiral polymers as well as homochiral small molecules where the side chain chirality had only a modest effect on the performance of organic solar cells and OTFTs. Diketopyrrolopyrroles (DPPs) offer an easily modifiable organic scaffold, which is among the most popular ones in organic electronics and widely used as OSC for OTFT and OPV applications .…”

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confidence: 84%

Impact of 2‐Ethylhexyl Stereoisomers on the Electrical Performance of Single‐Crystal Field‐Effect Transistors

Leowanawat

Burschka

et al. 2018

Advanced Materials

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Many organic semiconductors (OSCs) inherit chiral alkyl chains, which ensure the desirable high solubility for solution-processing but may also lead to disorder, inhomogeneous film-formation, as well as interfacial defects due to the presence of mixtures of stereoisomers or diastereomers, which impair their peak performance. Here, single-crystal field-effect transistors (SCFETs) of a diketopyrrolopyrrole-based organic semiconductor with chiral 2-ethylhexyl substituents by sublimation in air and organic ribbon mask method are fabricated. Devices of the mesomer (R/S), both enantiomers (R/R, S/S), as well as mixtures of these three stereoisomers measured under ambient conditions exhibit all appreciable p-channel charge carrier mobilities of > 0.1 cm V s despite different packing arrangement in the R/S, R/R (or S/S), and racemate crystal structures. These results suggest a surprising tolerance for isomeric impurities. The highest literature-reported p-channel mobility so far for a diketopyrrolopyrrole-based OSC of 3.4 cm V s (I /I of 1 × 10 ) is, however, only obtained for the pure R/S mesomer, illustrating the inherent potential of stereochemical purity. These results on SCFETs are further substantiated by studies on organic thin-film transistors (OTFTs) of pure and mixed thin films of the different stereoisomers.

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mentioning

confidence: 84%

Impact of 2‐Ethylhexyl Stereoisomers on the Electrical Performance of Single‐Crystal Field‐Effect Transistors

Leowanawat

Burschka

et al. 2018

Advanced Materials

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“…While chiral materials show remarkable self‐assembled nanostructures, in the context of functional materials for organic photovoltaic devices (OPVs) the influence of symmetry and stereochemistry possessed by molecular or polymeric components does not show any consistent trends . The degree and nature of molecular order in the active layer of OPVs is a vital factor influencing performance, where supramolecular arrangement influences morphology, exciton splitting and charge carrier mobility .…”

Section: Introductionmentioning

confidence: 99%

“…Atomic force microscopy of the blended thin films with the fullerene derivative usually employed (PC 61 BM) showed that smooth and well mixed films were achieved,w ith the conditions required during spin coating depending greatly on the derivative, because Introduction While chiral materials show remarkable self-assembled nanostructures, [1,2] in the context of functional materials for organic photovoltaic devices (OPVs)the influence of symmetry and stereochemistry possessedb ym olecular or polymeric components does not show any consistent trends. [3][4][5][6][7][8] The degree and natureo fm olecular order in the active layer of OPVs is av ital factori nfluencing performance, [9][10][11][12][13][14][15][16] where supramolecular arrangement [17] influences morphology,e xciton splitting and chargec arrierm obility. [18] In contrastt oo ther parameters, such as redox and optical characteristics, the molecular order in the active layer remains hard to control.I na ddition to p-p stacking of chromophores, currents trategies to improve device performance targeting molecular arrangementu tiliseh ydrogen bonding, [19][20][21] dipolar interactions [22] and other supramolecular approaches.…”

mentioning

confidence: 99%

Self‐Assembly of Chiral‐at‐End Diketopyrrolopyrroles: Symmetry Dependent Solution and Film Optical Activity and Photovoltaic Performance

Hume

Monks

Pop

et al. 2018

Chemistry A European J

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Chiral thiophene-diketopyrrolopyrrole derivatives have been synthesised to investigate the potential of stereochemistry and symmetry as a means of modulating properties by influencing self-assembly of these purely organic materials. In particular, derivatives of diketopyrrolopyrrole were employed because of their proven interest as dyes, especially for organic solar cells. The natural product myrtenal was used as the source of stereochemistry, introduced through a Kröhnke reaction of a thiophene-bearing pyridinium salt and diketopyrrolopyrroles were prepared through Suzuki coupling with this chiral moiety at one end only as well as at both ends. Absorption spectroscopy and electrochemistry confirmed the potential suitability of the compounds for photovoltaic devices. The nanostructures formed by the compounds have been probed with circular dichroism spectroscopy in solution and in films. It is shown that a chiral C symmetric molecule assembles in solution giving a strong circular dichroic signal while as a film this optical activity is nulled, whereas an asymmetric homologue is most optically active as a thin film. The X-ray crystal structure of the asymmetric compound shows a polar order of the molecules that might explain this observation. The lack of optical activity in solution is very likely a result of the high solubility of the compound. The results reaffirm the sensitivity of circular dichroism spectroscopy to inter-chromophore organisation, whereas absorption spectroscopy in the visible region reveals only slight changes to the bands. The differing order in the compounds also affects their performance in bulk heterojunction photovoltaic devices. Atomic force microscopy of the blended thin films with the fullerene derivative usually employed (PC BM) showed that smooth and well mixed films were achieved, with the conditions required during spin coating depending greatly on the derivative, because of their differing solubility. The apparently better performance of the symmetrical compound (although with very low efficiency) is probably a result of the alignment of the molecules inferred by the circular dichroism experiments, whereas the asymmetric compound presumably adopts a twisted supramolecular organisation.

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“…The electrochemical properties of two CPEs were studied by the cyclic voltammetry (CV) under the same conditions (Figure 2b). The highest occupied molecular orbitals (HOMO) of PBDTTh‐TT‐NBr and PBDT‐TT‐NBr were calculated to be −5.29 and −5.10 eV, respectively, similar to those of PTB7‐Th (−5.22 eV) and PTB7 (−5.14 eV),35 which indicated that the energy levels of the CPEs were not affected obviously by the quaternary ammonium groups.…”

Section: Optical and Electrochemical Properties Of Pbdt‐tt‐nbr And Pbmentioning

confidence: 80%

2D Conjugated Polyelectrolytes Possessing Identical Backbone with Active‐Layer Polymer as Cathode Interlayer for Organic Solar Cells

Nie

et al. 2020

Macromol. Rapid Commun.

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A 2D conjugated polyelectrolyte (CPE), PBDTTh‐TT‐NBr, having the same backbone as the highly efficient donor polymer PTB7‐Th and the quaternary ammonium pendant, is synthesized as a cathode interlayer (CIL) material for PTB7‐Th‐based fullerene and non‐fullerene solar cells. The quaternary ammonium group is connected to the 2D conjugated backbone by a long, flexible alkyl chain, facilitating the modification of cathode via forming interface dipoles. Moreover, compared with another CPE analogue to PTB7, PBDT‐TT‐NBr, without the 2D conjugated backbone, the PBDTTh‐TT‐NBr presents a higher similarity in polymer structure to the donor polymer PTB7‐Th. This feature makes it more compatible with the PTB7‐Th‐based active‐layer film, improving the electron transport. With the PBDTTh‐TT‐NBr as the CIL, devices afford higher performances than those using the PBDT‐TT‐NBr in both fullerene and non‐fullerene systems. This work offers guidance on choosing the CIL material that ought to possess a highly similar structure to the active‐layer component.

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Thieno[3,4-b]thiophene–benzo[1,2-b:4,5-b′]dithiophene-based polymers bearing optically pure 2-ethylhexyl pendants: Synthesis and application in polymer solar cells

Cited by 14 publications

References 53 publications

Impact of 2‐Ethylhexyl Stereoisomers on the Electrical Performance of Single‐Crystal Field‐Effect Transistors

Impact of 2‐Ethylhexyl Stereoisomers on the Electrical Performance of Single‐Crystal Field‐Effect Transistors

Self‐Assembly of Chiral‐at‐End Diketopyrrolopyrroles: Symmetry Dependent Solution and Film Optical Activity and Photovoltaic Performance

2D Conjugated Polyelectrolytes Possessing Identical Backbone with Active‐Layer Polymer as Cathode Interlayer for Organic Solar Cells

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