In situ X-ray characterization of oligophenylene thin films prepared by organic molecular beam deposition

Yoshida, Yūji; Takiguchi, Hiroshi; Hanada, Takeshi; Tanigaki, Nobutaka; Han, Eun Mi; Yase, Kiyoshi

doi:10.1016/s0169-4332(98)00133-0

Cited by 10 publications

(8 citation statements)

References 15 publications

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“…X-ray diffractograms of our films also show a series of 00 l peaks corresponding to the common polymorph of α-6P but also include a small shoulder on the low-angle side indicative of the recently found phase II. 43 Yoshida et al , recently reported that α-6P crystallized onto uniaxially oriented poly( p -phenylene) has its molecules and the (203) planes parallel to the substrate. For deposition onto alkali halide substrates, a different orientation was observed .…”

Section: Resultsmentioning

confidence: 99%

Morphological and Transistor Studies of Organic Molecular Semiconductors with Anisotropic Electrical Characteristics

Chen¹,

Lovinger²,

Bao³

et al. 2001

Chem. Mater.

117

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Oriented thin films of organic semiconducting small molecules were prepared by crystallization on rubbed alignment layers. Polarized absorption spectra showed that the long axis of the conjugated backbones was highly oriented along the rubbing direction and parallel to the substrates. Transmission electron microscopy and diffraction confirmed that the molecules and in many cases the resulting crystals are aligned. Using the above aligned films as semiconducting layers, we fabricated field-effect transistors having anisotropic mobilities with ratios greater than 15. Several common organic semiconductors have been investigated, and the results indicate that this growth method is generally successful for achieving macroscopic alignment of these semiconducting molecules (and frequently their crystals, as well).

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Section: Resultsmentioning

confidence: 99%

Morphological and Transistor Studies of Organic Molecular Semiconductors with Anisotropic Electrical Characteristics

Chen¹,

Lovinger²,

Bao³

et al. 2001

Chem. Mater.

117

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“…Huge efforts were made on the growth of p-6P on alkali halide surfaces like NaCl(100), KBr(100), KCl(100), NaF(100), and LiF(100) [79][80][81][82]. It turns out that the most defined growth morphology is formed on KCl (100).…”

Section: Sexiphenyl Thin Films On Dielectric Surfacesmentioning

confidence: 99%

Surface induced crystallographic order in sexiphenyl thin films

Resel¹

2008

J. Phys.: Condens. Matter

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The crystallographic order in sexiphenyl thin films on dielectric surfaces (like thermally oxidized silicon, KCl(100), TiO2(110) mica (001)) and on metallic surfaces (like Au(111), Al(111)) are summarized. The combination of the surface science studies considering the first molecular layers on the substrate surfaces with crystallographic studies on sexiphenyl films reveals the influence of the first molecular layers on the thin-film structure. The interaction strength of the molecules with the substrate has a large influence on the preferred orientation of the crystallites relative to the substrate surface. In the case of metallic surfaces, the orientation of the molecules at the first monolayer determines the alignment of the crystallites in the thin film. In the case of dielectric surfaces, other types of preferred crystal orientations are observed, which is connected with the increasing importance of the intermolecular interaction strength in the first monolayers. Generally, it is observed that the bulk crystal structure is already present in thin films with a nominal thickness slightly larger than the monolayer thickness. The orientation and alignment of the initial crystal clusters at the surface determine the layer growth. The thin films show specific morphologies: depending on the orientation of the molecules relative to the substrate surface, either terraced islands or needle-like structures appear. The crystallite size parallel to the surface varies in a range from nanometres up to several tens of microns, depending on the type of substrate and the thin-film growth conditions. In the case of terraced islands, the crystallite size perpendicular to the surface is comparable with the nominal film thickness.

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“…[1][2][3][4] In the thin films the molecules exhibit either vertical or parallel molecular alignment to the substrate plane. 5 Intermediately disordered morphologies (amorphous or amorphous-like states) can also be found. 6 As a general trend, short molecules tend to take the vertical alignment, whereas the parallel alignment prevails with increasing molecular lengths.…”

Section: Introductionmentioning

confidence: 99%

“…Conjugated oligomers such as oligothiophenes and oligophenylenes have recently been attracting much attention because of their well-defined molecular lengths and controllable electronic states. These materials are being applied to electronic and optical devices such as thin-film transistors and light-emitting diodes. − In the thin films the molecules exhibit either vertical or parallel molecular alignment to the substrate plane .…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Features of Thin Films of Thiophene/Phenylene Co-oligomers with Vertical Molecular Alignment

Hotta¹,

Ichino²,

Yoshida³

et al. 2000

J. Phys. Chem. B

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Spectroscopic features of various thiophene/phenylene co-oligomers with various molecular sizes and shapes have been investigated in the form of thin films. Of these compounds, shorter oligomers assume the vertical molecular alignment more readily than longer oligomers. The latter oligomers, however, tend to exhibit the vertical alignment when deposited under a high vacuum and at a small deposition rate. The thin films of this alignment were examined by the θ-2θ X-ray diffraction and incident-angle-dependent polarized absorption spectroscopy. A sharpened spectral line markedly grows around 300 nm in the polarized absorption spectra with increasing incident angles. We assign this line to the upper Davydov level and estimate the magnitude of the Davydov splitting on the basis of energetic consideration of the spectra in combination with the results of quantum chemical calculations.

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In situ X-ray characterization of oligophenylene thin films prepared by organic molecular beam deposition

Cited by 10 publications

References 15 publications

Morphological and Transistor Studies of Organic Molecular Semiconductors with Anisotropic Electrical Characteristics

Morphological and Transistor Studies of Organic Molecular Semiconductors with Anisotropic Electrical Characteristics

Surface induced crystallographic order in sexiphenyl thin films

Spectroscopic Features of Thin Films of Thiophene/Phenylene Co-oligomers with Vertical Molecular Alignment

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