Synthesis of Isomerically Pure <i>anti</i>-Anthradithiophene Derivatives

Tylleman, Benoît; Velde, Christophe M. L. Vande; Balandier, Jean‐Yves; Stas, Sara; Sergeyev, Sergey; Geerts, Yves

doi:10.1021/ol202089t

Cited by 42 publications

(36 citation statements)

References 29 publications

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“…[18, 34–36] We thus employed our vibration-assisted crystallization (VAC) method, in which the semiconductor solution is perturbed with gentle vibrations applied during film growth in a direction perpendicular to the substrate. [12] In an earlier report, we showed that this procedure yields lower trap densities and enhanced device performance by promoting molecular assembly in a lowest-potential energy configuration.…”

Section: Resultsmentioning

confidence: 99%

The Influence of Isomer Purity on Trap States and Performance of Organic Thin‐Film Transistors

Diemer

Hayes

Welchman

et al. 2016

Adv Elect Materials

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Organic field-effect transistor (OFET) performance is dictated by its composition and geometry, as well as the quality of the organic semiconductor (OSC) film, which strongly depends on purity and microstructure. When present, impurities and defects give rise to trap states in the bandgap of the OSC, lowering device performance. Here, 2,8-difluoro-5,11-bis(triethylsilylethynyl)-anthradithiophene is used as a model system to study the mechanism responsible for performance degradation in OFETs due to isomer coexistence. The density of trapping states is evaluated through temperature dependent current-voltage measurements, and it is discovered that OFETs containing a mixture of syn- and anti-isomers exhibit a discrete trapping state detected as a peak located at ~ 0.4 eV above the valence-band edge, which is absent in the samples fabricated on single-isomer films. Ultraviolet photoelectron spectroscopy measurements and density functional theory calculations do not point to a significant difference in electronic band structure between individual isomers. Instead, it is proposed that the dipole moment of the syn-isomer present in the host crystal of the anti-isomer locally polarizes the neighboring molecules, inducing energetic disorder. The isomers can be separated by applying gentle mechanical vibrations during film crystallization, as confirmed by the suppression of the peak and improvement in device performance.

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Section: Resultsmentioning

confidence: 99%

The Influence of Isomer Purity on Trap States and Performance of Organic Thin‐Film Transistors

Diemer

Hayes

Welchman

et al. 2016

Adv Elect Materials

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“…Thus the chemical community has adopted much lengthier synthetic approaches to synthesize each pure isomer directly. Geerts and co‐workers were the first to explore pure ADT isomers, developing an elegant synthesis of pure anti dihexyl ADT with an overall chemical yield of ≈3% in 2011 . Unfortunately, there have been no reports of the device performance/hole transport property measurement for this material.…”

Section: Introductionmentioning

confidence: 99%

Structural and Electronic Properties of Crystalline, Isomerically Pure Anthradithiophene Derivatives

Hallani

Thorley

Mei

et al. 2015

Adv Funct Materials

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considering that the majority of devices based on ADTs reported to date have been formed from a material consisting of a mixture of isomers. Typically, isomeric mixtures are expected to offer decreased electronic performance, due to the inhomogeneities in intermolecular order that arise in the crystalline state. [ 6 ] The isomer mixtures ( mix ADTs) arise due to the nonregiospecifi c aldol condensation used in the most common synthesis of the ADT chromophore. [ 7 ] Even in the case of highly soluble ADT derivatives, separation of the syn and anti isomers after synthesis has proven impossible. Thus the chemical community has adopted much lengthier synthetic approaches to synthesize each pure isomer directly. Geerts and co-workers were the fi rst to explore pure ADT isomers, developing an elegant synthesis of pure anti dihexyl ADT with an overall chemical yield of ≈3% in 2011. [ 8 ] Unfortunately, there have been no reports of the device performance/hole transport property measurement for this material. In 2012, the Tykwinski group demonstrated the fi rst synthesis of pure syn diF TES ADT, in an overall yield of 9% from commercial starting materials. [ 9 ] Single-crystal studies by Jurchescu and co-workers showed no signifi cant difference in charge transport properties between the mix and syn materials.More recently, Takimiya and co-workers prepared the parent ADT in isomerically pure anti form in six synthetic steps and 43% overall yield, [ 10 ] and found that the transistor performance was several times higher than that of the isomeric mixture reported by Katz [ 1 ] (although some of this improvement may arise due to improved modern device fabrication protocols). Mamada and co-workers prepared both isomeric forms of the parent ADT, in 12% overall yield for anti and 7% yield for syn . [ 11 ] In vacuum-deposited devices, the anti isomer showed substantially higher performance than the syn isomer; 0.18 cm 2 V −1 s −1 compared to 0.017 cm 2 V −1 s −1 for syn . Similarly, Takimiya and co-workers also observed an order-of-magnitude difference in hole transport effi ciency between alkylated isomerically pure anti-and syn-naphthodithiophenes, with the anti derivative again exhibiting better performance. [ 12 ] These results strongly suggest that a detailed understanding of the impact of isomer mixtures in the solution-processable, ethyne-substituted ADTs will not be complete without side-by-side analysis of the mix , syn , and heretofore-elusive pure anti isomers. Structural and Electronic Properties of Crystalline, Isomerically Pure Anthradithiophene DerivativesRawad K. Hallani , Karl J. Thorley , Yaochuan Mei , Sean R. Parkin , Oana D. Jurchescu , and John E. Anthony * Anthradithiophene chromophores are found in many current high-performance organic semiconductors, even though these materials are typically synthesized as an inseparable mixture of syn and anti isomers. Recent syntheses of pure syn anthradithiophenes have shown no improvement in performance for the more homogeneous system, but similar studies on the ...

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“…Although ADTs are usually prepared as a mixture of isomers, ADTs can also be prepared as pure syn and anti isomers due to recent advances in synthesis and purification procedures. [10a‐e,12] We use a heavily modified version of these approaches to prepare, for the first time, pure syn and anti TES ADT. Despite differences in the single‐crystal structures of syn and anti TES ADT, each forms spherulites 1–4 cm in diameter upon solvent‐vapor annealing.…”

mentioning

confidence: 99%

Understanding the Crystal Packing and Organic Thin‐Film Transistor Performance in Isomeric Guest–Host Systems

et al. 2017

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In order to understand how additives influence the structure and electrical properties of active layers in thin-film devices, a compositionally identical but structurally different guest-host system based on the syn and anti isomers of triethylsilylethynyl anthradithiophene (TES ADT) is systematically explored. The mobility of organic thin-film transistors (OTFTs) comprising anti TES ADT drops with the addition of only 0.01% of the syn isomer and is pinned at the mobility of OTFTs having pure syn isomer after the addition of only 10% of the isomer. As the syn isomer fraction increases, intermolecular repulsion increases, resulting in a decrease in the unit-cell density and concomitant disordering of the charge-transport pathway. This molecular disorder leads to an increase in charge trapping, causing the mobility of OTFTs to drop with increasing syn-isomer concentration. Since charge transport is sensitive to even minute fractions of molecular disorder, this work emphasizes the importance of prioritizing structural compatibility when choosing material pairs for guest-host systems.

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Synthesis of Isomerically Pure anti-Anthradithiophene Derivatives

Abstract: The regiospecific total synthesis and characterization of anti-isomers of 2,8-dialkylanthradithiophenes are described. The "anti" structure of the ADT derivatives is demonstrated by 13 C NMR as well as single crystal X-ray diffraction.

Cited by 42 publications

References 29 publications

The Influence of Isomer Purity on Trap States and Performance of Organic Thin‐Film Transistors

The Influence of Isomer Purity on Trap States and Performance of Organic Thin‐Film Transistors

Structural and Electronic Properties of Crystalline, Isomerically Pure Anthradithiophene Derivatives

Understanding the Crystal Packing and Organic Thin‐Film Transistor Performance in Isomeric Guest–Host Systems

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