Fabrication of Highly Oriented Rubrene Thin Films by the Use of Atomically Finished Substrate and Pentacene Buffer Layer

Haemori, Masamitsu; Yamaguchi, Jun; Yaginuma, Seiichiro; Itaka, Kenji; Koinuma, Hideomi

doi:10.1143/jjap.44.3740

Cited by 61 publications

(51 citation statements)

References 15 publications

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“…In an alternative approach, which has been at first suggested by Haemori and co-workes, we succeeded to generate crystallization by use of a suited seed-layer, in this case a monolayer of pentacene [15,16]. With respect to the transistor measurements discussed below it is important to note that the pentacene seed-layer does not form a closed monolayer on the SiO 2 substrate.…”

Section: Recrystallization Of Rubrene Layersmentioning

confidence: 99%

Thermally and seed‐layer induced crystallization in rubrene thin films

Nothaft

Pflaum

2008

Physica Status Solidi (b)

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We have analyzed the tendency of crystallization and the thermal activation of ordering processes in rubrene thin films. As we will demonstrate, a crystalline phase with a unit cell in agreement to the bulk structure can be stabilized upon heating of amorphous rubrene layers previously capped by a sputtered SiOx layer. This encapsulation significantly enhances the thermal stability of the organic film by about 150 °C. We compared this approach with crystallization initiated by the presence of a pentacene seed layer during rubrene deposition. Thin film transistors prepared by this route showed hole mobilities of 0.01 cm2/Vs which are four orders of magnitude higher than for their amorphous counterparts. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Recrystallization Of Rubrene Layersmentioning

confidence: 99%

Thermally and seed‐layer induced crystallization in rubrene thin films

Nothaft

Pflaum

2008

Physica Status Solidi (b)

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“…It has been reported that the choice of the substrate strongly influences the growth of rubrene thin films. [13][14][15][16][17][18] Moreover, the deposition technique can also lead to different results. In particular, the conformation of the rubrene molecules may play an important role in the thin film growth.…”

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Three-Dimensional Chirality Transfer in Rubrene Multilayer Islands on Au(111)

et al. 2009

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The growth of rubrene (C(42)H(28), 5,6,11,12-tetraphenylnaphthacene) multilayer islands up to a thickness of six layers on a Au(111) surface has been investigated by scanning tunneling microscopy. The molecules self-organize in parallel twin rows, forming mirror domains of defined local structural chirality. Each layer is composed of twin-row domains of the same structural handedness rotated by 120 degrees with respect to each other. Moreover, this structural chirality is transferred to all successive layers in the island, resulting in the formation of three-dimensional objects having a defined structural chirality. The centered rectangular surface unit cell differs from the one characteristic for the single-crystal orthorhombic phase.

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“…[20] In addition, we have observed a similar crystallization effect in 5,6,11,12-tetraphenylnaphthacene (rubrene) films grown on pentacene buffers. [21] These surface modifications are applicable to many different substrate surfaces and organic compounds with poor wettability. In order to realize unipolar FETs, the next stage of this study should be trying to combine active layers and wetting-control buffers of the same type (p-n).…”

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High‐Mobility C₆₀ Field‐Effect Transistors Fabricated on Molecular‐ Wetting Controlled Substrates

et al. 2006

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Organic thin-film devices are of interest for a variety of forthcoming ubiquitous electronic applications. [1,2] In order to take full advantage of the potential of organic semiconductors, the improvement of crystallinity is indispensable. Unfortunately, promising organic molecules that have a large overlap of p-orbitals between the molecules cannot migrate freely on a substrate [3] because of the stronger cohesion between the molecules than the interaction between the molecule and the substrate. Therefore, enhancement of the molecule-substrate interaction, that is, the 'molecular wettability' should promote crystallization. Here, we show that the use of a substrate covered with an atomically flat pentacene (C 22 H 14 ) monomolecular layer can drastically increase the crystallinity of C 60 films and increase the field-effect mobilities of C 60 transistors to 2.0-4.9 cm 2 V -1 s -1 , which is a four-to fivefold improvement over C 60 films grown without a pentacene buffer. The observation of the initial growth stages indicates that control of the molecular wettability of the substrate by an atomically flat pentacene buffer caused the improvement of crystallinity in the C 60 films. Molecular-wetting-controlled substrates can thus offer a general solution to the fabrication of high-performance crystalline plastic and molecular-electronic applications. In order to fabricate complex electronic devices such as field-effect transistors (FETs), for ubiquitous electronics, organic thin films need to be grown on many different substrate materials to fit the requirements of particular applications.However, most organic compounds grown on such practical substrates as oxide dielectrics show a poor crystallinity. Because poor crystallinity of the active layers suppresses the device performance markedly, crystalline organic films that have good crystallinity and few grain boundaries are required for a high-performance operation. The molecular wettability of a substrate controls the distance of the lateral migration of the molecules at the film growth front and thus largely determines the morphology of the growing film. The wettability on a substrate surface is determined by the ratio of the cohesion strength among the molecules and the adhesion of the molecules to the substrate surface, as shown in Figure 1a. If the balance between the cohesion and adhesion forces could be controlled by inserting a thin buffer layer, we would expect to obtain organic films with improved crystallinity. Surface modification of a substrate by self-assembled monolayers (SAMs) has been used for the suppression of disorder in organic films near electrodes, [4] and for controlling the carrier density in organic FETs.

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Fabrication of Highly Oriented Rubrene Thin Films by the Use of Atomically Finished Substrate and Pentacene Buffer Layer

Cited by 61 publications

References 15 publications

Thermally and seed‐layer induced crystallization in rubrene thin films

Thermally and seed‐layer induced crystallization in rubrene thin films

Three-Dimensional Chirality Transfer in Rubrene Multilayer Islands on Au(111)

High‐Mobility C₆₀ Field‐Effect Transistors Fabricated on Molecular‐ Wetting Controlled Substrates

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Fabrication of Highly Oriented Rubrene Thin Films by the Use of Atomically Finished Substrate and Pentacene Buffer Layer

Cited by 61 publications

References 15 publications

Thermally and seed‐layer induced crystallization in rubrene thin films

Thermally and seed‐layer induced crystallization in rubrene thin films

Three-Dimensional Chirality Transfer in Rubrene Multilayer Islands on Au(111)

High‐Mobility C60 Field‐Effect Transistors Fabricated on Molecular‐ Wetting Controlled Substrates

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High‐Mobility C₆₀ Field‐Effect Transistors Fabricated on Molecular‐ Wetting Controlled Substrates