A Computational Study of the Sub-monolayer Growth of Pentacene

Choudhary, Devashish; Clancy, Paillette; Shetty, Ritesh; Escobedo, Fernando A.

doi:10.1002/adfm.200500148

Cited by 51 publications

(72 citation statements)

References 26 publications

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“…It is plausible to associate the delay in the onset of tilting with the lack of adjacent molecules to form the seeds of this upright phase in the beginning of the growth process. These findings are in accord with the computational study of submonolayer growth of Pn by Choudhary et al;20 once a critical nucleus of Pn is formed under favorable conditions, the molecules tend to flip up from flat lying to upright orientation at the onset of aggregation resulting in the formation of a crystalline phase.…”

Section: Resultssupporting

confidence: 91%

“…However, the exact morphology of the Pn films can vary significantly depending on the bonding to the surface. 20 Another possible route toward reshaping the structure of the molecular film in a controllable way is to use a nanopatterned substrate with a periodic variation in the electrostatic potential along the surface. In particular, inert substrates with a strong periodic corrugation may be promising as templates for producing films with a desired motif because weakly bonded self-assembled molecular monolayers can be easily affected by lateral inhomogeneities.…”

Section: Introductionmentioning

confidence: 99%

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Effect of substrate nanopatterning on the growth and structure of pentacene films

Preobrajenski

Zakharov

et al. 2010

Phys. Rev. B

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The effect of modulating the structure of thin pentacene ͑C 22 H 14 ͒ films by a nanopatterned inert substrate, known as hexagonal boron nitride nanomesh, is reported. Films of different thickness are grown and characterized by x-ray absorption, core-level photoemission, low-energy electron microscopy, microbeam low-energy electron diffraction, and scanning tunneling microscopy. Initially the pentacene molecules adsorb with the molecular plane lying flat on the substrate but they tend to flip up with increasing coverage, forming wellordered monolayer-thick islands of upright molecules with low nucleation density. The herringbone packing of the upright molecules is observed with scanning tunneling microscopy. The electronic structure of the adsorbed molecules is very similar to that of the gas-phase pentacene, implying weak interaction with the substrate and between the molecules. The periodic corrugation of the substrate surface causes the monolayer of upright pentacene molecules to form two different coincidence superstructures. The lattice parameters of the pentacene unit cell for each of these two substrate-induced domains are determined from the microdiffraction patterns. Both domains can occur in several equivalent configurations, thus resulting in a number of twins with a typical size of a few micrometers. The first monolayer grows in a layer-by-layer mode until it is completed while the second monolayer forms diffusion-limited fractal islands. Upon annealing, the pentacene films are thermally stable up to approximately 80°C and thereafter the onset of desorption is observed.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Effect of substrate nanopatterning on the growth and structure of pentacene films

Preobrajenski

Zakharov

et al. 2010

Phys. Rev. B

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“…Within the few existing MC studies of anisotropic molecules at interfaces, the molecules' orientations are typically strongly restricted; e.g., molecules are modelled by strings occuping multiple lattice sites [29][30][31], or the orientations are restricted to a 2D plane [32] (note that the latter study also considers the influence of a striped substrate). Such restrictions are inappropriate for 6P at ZnO, where it is known from experiments that the molecules can explore the full, 3D space of orientations [14].…”

Section: Introductionmentioning

confidence: 99%

A scale-bridging modeling approach for anisotropic organic molecules at patterned semiconductor surfaces

Kleppmann

Klapp

2015

The Journal of Chemical Physics

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Hybrid systems consisting of organic molecules at inorganic semiconductor surfaces are gaining increasing importance as thin film devices for optoelectronics. The efficiency of such devices strongly depends on the collective behavior of the adsorbed molecules. In the present paper we propose a novel, coarse-grained model addressing the condensed phases of a representative hybrid system, that is, para-sexiphenyl (6P) at zinc-oxide (ZnO). Within our model, intermolecular interactions are represented via a Gay-Berne potential (describing steric and van-der-Waals interactions) combined with the electrostatic potential between two linear quadrupoles. Similarly, the molecule-substrate interactions include a coupling between a linear molecular quadrupole to the electric field generated by the line charges characterizing ZnO(10-10). To validate our approach, we perform equilibrium Monte Carlo simulations, where the lateral positions are fixed to a 2D lattice, while the rotational degrees of freedom are continuous. We use these simulations to investigate orientational ordering in the condensed state. We reproduce various experimentally observed features such as the alignment of individual molecules with the line charges on the surface, the formation of a standing uniaxial phase with a herringbone structure, as well as the formation of a lying nematic phase.

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“…27 The precise understanding and quantification of this growth behavior requires specialized modeling tools such as kinetic Monte-Carlo simulations that combine all of the microscopic events described above. 28,29 This is left to further work. For large apertures of a = 10 µm, this diffusion-driven growth is not observed.…”

mentioning

confidence: 99%

Arrays of Pentacene Single Crystals by Stencil Evaporation

Fesenko

Flauraud

Xie

et al. 2016

Crystal Growth & Design

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In order to realize high-performance organic thin-film transistors (TFT), two parameters of the organic semiconducting layer are desired: single crystallinity for high mobility, and patterning for low off currents. High-quality single crystals can be fabricated using vapor techniques such as physical vapor transport (PVT) but they require high temperatures close to thermodynamic 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 equilibrium, for example, 240°C for pentacene. Such high temperatures are not ideal for TFT fabrication on plastic substrates and limit the use of PVT in flexible electronics applications.In this work arrays of pentacene single crystals were directly deposited at low temperature of 40°C by vacuum thermal evaporation through micro-fabricated stencil masks (stencil lithography). By decreasing the stencil aperture size down to 1 µm x 1 µm, we were able to limit the nucleation area until only one grain per aperture is nucleated and grown. We studied systematically scaling effects for large singe crystal growth and discuss details of the growth morphology. We found for instance that the formed pentacene crystals are one monolayer thick and the crystal area is much larger than the aperture size. This can be explained by the diffusion of adsorbed molecules on the surface laterally under the shadow mask, where they are protected from other impinging molecules. The diffusion away from the impinging area under the aperture affects the nucleation density inside this area and was used to calculate the diffusion length to nucleation λ N = 0.66 ± 0.11 µm of pentacene on SiO 2 at 40°C. Our diffusion-driven growth of organic single crystals by stencil lithography is a direct method to grow patterned arrays of single crystalline organic thin-film semiconductor layers.

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A Computational Study of the Sub-monolayer Growth of Pentacene

Cited by 51 publications

References 26 publications

Effect of substrate nanopatterning on the growth and structure of pentacene films

Effect of substrate nanopatterning on the growth and structure of pentacene films

A scale-bridging modeling approach for anisotropic organic molecules at patterned semiconductor surfaces

Arrays of Pentacene Single Crystals by Stencil Evaporation

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