Large uniaxial negative thermal expansion in pentacene due to steric hindrance

Haas, Simon; Batlogg, B.; Besnard, Céline; Schiltz, M.; Kloc, Christian; Siegrist, T.

doi:10.1103/physrevb.76.205203

Cited by 81 publications

(79 citation statements)

References 25 publications

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“…The obtained librational motion of pentacene using the DFT-D approach is shown in Fig. 1(b) as a function of temperature, which is in good agreement with the results of the TLS analysis of crystal structures in the present and the previous 16 experimental observations.…”

supporting

confidence: 79%

Correlation between thermal fluctuation effects and phase coherence factor in carrier transport of single-crystal organic semiconductors

Fukami

Ishii

Kobayashi

et al. 2015

Applied Physics Letters

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We find that the phase coherence factor derived from Hall effect measurements of single-crystal thin-film field-effect transistors of pentacene, which relates the intrinsic charge transport with the phase coherence, has a strong correlation with the thermal fluctuations of transfer energies between neighboring molecules. This observation also holds true for other organic semiconductors such as tetracene, dianthrathiophene (DAT)-V, and dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT). This gives us clues for constructing flexible molecular systems with high carrier mobility.

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supporting

confidence: 79%

Correlation between thermal fluctuation effects and phase coherence factor in carrier transport of single-crystal organic semiconductors

Fukami

Ishii

Kobayashi

et al. 2015

Applied Physics Letters

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“…This observation becomes clear considering the interlocked heptafluorobutyl groups of adjacent molecules in the a-phase, which impose a severe constraint on the spatial expansion at elevated temperatures. As a result of the pronounced thermal expansion along the a-and c-axes of the b-phase in combination with a weak intermolecular interaction, the b-direction shows even a slight compression upon heating a b ¼ À 0.2 Â 10 À 4 K À 1 , which refers to a superimposed rotation of molecules 37 ARTICLE might be considered as reference temperature for the intrinsic a-to b-phase transition without superimposed effects by latent heat or kinetic hindrances.…”

Section: Resultsmentioning

confidence: 99%

Single-crystal field-effect transistors of new Cl2-NDI polymorph processed by sublimation in air

et al. 2015

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Physical properties of active materials built up from small molecules are dictated by their molecular packing in the solid state. Here we demonstrate for the first time the growth of n-channel single-crystal field-effect transistors and organic thin-film transistors by sublimation of 2,6-dichloro-naphthalene diimide in air. Under these conditions, a new polymorph with two-dimensional brick-wall packing mode (b-phase) is obtained that is distinguished from the previously reported herringbone packing motif obtained from solution (a-phase). We are able to fabricate single-crystal field-effect transistors with electron mobilities in air of up to 8.6 cm 2 V À 1 s À 1 (a-phase) and up to 3.5 cm 2 V À 1 s À 1 (b-phase) on n-octadecyltriethoxysilane-modified substrates. On silicon dioxide, thin-film devices based on b-phase can be manufactured in air giving rise to electron mobilities of 0.37 cm 2 V À 1 s À 1 . The simple crystal and thin-film growth procedures by sublimation under ambient conditions avoid elaborate substrate modifications and costly vacuum equipment-based fabrication steps.

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“…The orientation of the cellobiose chain in the x 1 -x 2 plane and the identification of the role of rotation of these chains about the x 3 -axis is analogous to the mechanism proposed for anisotropic (including negative) thermal expansion in pentacene crystals (Haas et al 2007). The tilt angle identified in this work is analogous to the herringbone angle describing the packing of the assumed rigid pentacene molecules.…”

Section: Discussionmentioning

confidence: 99%

Modeling of negative Poisson’s ratio (auxetic) crystalline cellulose Iβ

Yao

Alderson²,

Alderson

2016

Cellulose

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Energy minimizations for unstretched and stretched cellulose models using an all-atom empirical force field (molecular mechanics) have been performed to investigate the mechanism for auxetic (negative Poisson's ratio) response in crystalline cellulose I b from kraft cooked Norway spruce. An initial investigation to identify an appropriate force field led to a study of the structure and elastic constants from models employing the CVFF force field. Negative values of on-axis Poisson's ratios m 31 and m 13 in the x 1 -x 3 plane containing the chain direction (x 3 ) were realized in energy minimizations employing a stress perpendicular to the hydrogen-bonded cellobiose sheets to simulate swelling in this direction due to the kraft cooking process. Energy minimizations of structural evolution due to stretching along the x 3 chain direction of the 'swollen' (kraft cooked) model identified chain rotation about the chain axis combined with inextensible secondary bonds as the most likely mechanism for auxetic response.

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Large uniaxial negative thermal expansion in pentacene due to steric hindrance

Cited by 81 publications

References 25 publications

Correlation between thermal fluctuation effects and phase coherence factor in carrier transport of single-crystal organic semiconductors

Correlation between thermal fluctuation effects and phase coherence factor in carrier transport of single-crystal organic semiconductors

Single-crystal field-effect transistors of new Cl2-NDI polymorph processed by sublimation in air

Modeling of negative Poisson’s ratio (auxetic) crystalline cellulose Iβ

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