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

Abstract

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 repre- sented 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.

arXiv comment15 pages, 14 figures

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Cited by in corpus (6)

• Monolayers of hard rods on planar substrates: II. Growth
• Impact of anisotropic interactions on non-equilibrium cluster growth at surfaces
• Modeling of nonequilibrium surface growth by a limited mobility model with distributed diffusion length
• Non-equilibrium surface growth in a hybrid inorganic-organic system
• Equilibrium structures of anisometric, quadrupolar particles confined to a monolayer
• Coarse-graining strategy for molecular pair interactions: A reaction coordinate study for two- and three-dimensional systems