Role of Surface Electronic Structure in Thin Film Molecular Ordering

Abstract

We show that the orientation of pentacene molecules is controlled by the electronic structure of the surface on which they are deposited. We suggest that the near-Fermi level density of states above the surface controls the interaction of the substrate with the pentacene pi orbitals. A reduction of this density as compared to noble metals, realized in semimetallic Bi(001) and Si(111)(5 x 2)Au surfaces, results in pentacene standing up. Interestingly, pentacene grown on Bi(001) is highly ordered, yielding the first vertically oriented epitaxial pentacene thin films observed to date.

Small-angle lattice rotations in graphene on Ru(0001)

“…35,36 In μLEED, diffraction information from a very small selected area is obtained by restricting the size of the electron beam that is incident on the sample. [35][36][37][38] This is done in a LEEM instrument by placing a small aperture in the beam path. The beam size is further reduced by the demagnification (∼20×) of the objective lens.…”

Molecular Orientation and Ordering during Initial Growth of Copper Phthalocyanine on Si(111)

“…The nucleation and growth of organic molecular thin film systems has been shown to demonstrate qualitative differences to that for inorganic systems [1][2][3][4] . The orientational degree of freedom for molecules with respect to the lying-down () and standing-up () configurations during the growth of organic films is one of the most important differences 2 .…”

“…Such disorder in the growth of molecular systems can affect their electronic transport properties 5 . Whilst the growth of inorganic systems is now understood with a certain level of sophistication, the understanding of new effects introduced by orientational and conformational degrees of freedom on the growth of molecular systems is in its infancy [1][2][3][4][6][7][8] .…”

Organic Molecules on Noble Metal Surfaces: The Role of the Interface

“…The orientation of pentacene molecules is controlled by the electronic structure of the substrate, namely the near-Fermi level density of states above the surface controls the interaction of the substrate with the pentacene π orbitals. A reduction of this density, as compared to noble metals, realized in semimetallic Bi(001) and Si(111)(5×2)Au surfaces, results in pentacene standing up (Thayer 2005).…”