Electronic charge rearrangement at metal/organic interfaces induced by weak van der Waals interactions

Abstract

Electronic charge rearrangements at interfaces between organic molecules and solid surfaces play a key role in a wide range of applications in catalysis, light-emitting diodes, single-molecule junctions, molecular sensors and switches, and photovoltaics. It is common to utilize electrostatics and Pauli pushback to control the interface electronic properties, while the ubiquitous van der Waals (vdW) interactions are often considered to have a negligible direct contribution (beyond the obvious structural relaxation). Here, we apply a fully self-consistent Tkatchenko-Scheffler vdW density functional to demonstrate that the weak vdW interactions can induce sizable charge rearrangements at hybrid metal/organic systems (HMOS). The complex vdW correlation potential smears out the interfacial electronic density, thereby reducing the charge transfer in HMOS, changes the interface work functions by up to 0.2 eV, and increases the interface dipole moment by up to 0.3 Debye. Our results suggest that vdW interactions should be considered as an additional control parameter in the design of hybrid interfaces with the desired electronic properties.

The supramolecular structure and van der Waals interactions affect the electronic structure of ferrocenyl-alkanethiolate SAMs on gold and silver electrodes

“…96 It is well-known that the change in the work function, Df, of the bare metal substrate, due to molecular adsorption reects the change in the surface potential through the formation of interface dipoles (IDs) composed of the bond dipole, m bond , resulting from charge redistribution induced by electronic interactions between molecular adsorbates and metal substrates, and intrinsic molecular dipoles of the SAM molecules projected along surface normal, m mol . 13,44,[97][98][99] Therefore, the molecules, once adsorbed on the metal surface, induce a change in work function of metal surface Df which can be expressed as:…”

Tailoring van der Waals dispersion interactions with external electric charges

“…This indicates that both static and dynamic intermolecular interactions must be treated on an equal footing, and that the QDO model 23 – 26 provides an adequate approach that includes proper coupling between electrostatics, polarization, and dispersion for systems in isolation or subject to external fields. As vdW dispersion interactions can also have a direct effect on the electron charge distribution in large molecules and materials 63 , 64 , we emphasize the need to treat classical electrostatics and quantum vdW interactions in a unified and self-consistent manner. Only such advanced methods will ultimately allow to achieve predictive power in atomistic modeling of complex molecular materials.…”

Salient signature of van der Waals interactions

“…On the other hand, the effect of vdW interactions in the wavefunction or related quantities has been less discussed in the literature. [13][14][15][16] This knowledge could shed some light in the design of computational approaches including vdW interactions and provide further tests to calibrate electronic structure theory methods.…”

“…On the other hand, the effect of vdW interactions in the wavefunction or related quantities has been less discussed in the literature. [13][14][15][16] This knowledge could shed some light in the design of computational approaches including vdW interactions and provide further tests to calibrate electronic structure theory methods.In this letter we use perturbation theory to find the leading term in the expansion of the intracule pair density in terms of R, the interatomic distance. Our results reveal a universal 1/R 3 dependency that is corroborated by numerical calculations in H 2 and He 2 molecules.…”