Field of Expertise: Advanced Material Science
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Field of Expertise: Advanced Material Science | |
Impact of the interplay of van der Waals interactions, surface reconstructions and coverage on electronic and structural properties of self-assembled monolayers The deposition of self-assembled monolayers (SAMs) is an efficient way of tuning the properties of interfaces. SAMs can be adsorbed on or covalently bound to an underlying metallic substrate. Even if such systems are stabilized by being covalently linked, van der Waals interactions play an essential role in the assembly of upright standing molecules into SAMs. Also binding-induced surface-reconstructions and the effective surface coverage have been shown to strongly affect their electronic and structural properties.1,2 In addition, changing the tail-group substituents from electron-donating (-CH3) to -withdrawing (-CN, -CF3) groups can have a strong effect on the response of the self-assembled system to such structural rearrangements.3,4 Here we use density functional theory based, slab-type band-structure calculations to investigate the impact of vdW interactions on the interrelation of structural and electronic properties. To that aim, we study various ad-atom geometries discussed in literature1 and vary coverage and tail-group substitution for aromatic thiolate-bonded SAMs on the Au(111) surfaces. We find a significant impact of surface-reconstructions and coverage on the SAM electronic properties with the observed variations typically increasing when including vdW interactions. |