Control of Molecular Organization and Energy Level Alignment by an Electronically Nanopatterned Boron Nitride Template

Abstract

Suitable templates to steer the formation of nanostructure arrays on surfaces are indispensable in nanoscience. Recently, atomically thin sp(2)-bonded layers such as graphene or boron nitride (BN) grown on metal supports have attracted considerable interest due to their potential geometric corrugation guiding the positioning of atoms, metallic clusters or molecules. Here, we demonstrate three specific functions of a geometrically smooth, but electronically corrugated, sp(2)/metal interface, namely, BN/Cu(111), qualifying it as a unique nanoscale template. As functional adsorbates we employed free-base porphine (2H-P), a prototype tetrapyrrole compound, and tetracyanoquinodimethane (TCNQ), a well-known electron acceptor. (i) The electronic moirons of the BN/Cu(111) interface trap both 2H-P and TCNQ, steering self-organized growth of arrays with extended molecular assemblies. (ii) We report an effective decoupling of the trapped molecules from the underlying metal support by the BN, which allows for a direct visualization of frontier orbitals by scanning tunneling microscopy (STM). (iii) The lateral molecular positioning in the superstructured surface determines the energetic level alignment; i.e., the energy of the frontier orbitals, and the electronic gap are tunable.

Striped, honeycomb, and twisted moiré patterns in surface adsorption systems with highly degenerate commensurate ground states

“…Understanding and predicting these states and the transition between them has been of great fundamental interest for many years. Most recently there has been considerable work devoted to the study of the growth and properties of two-dimensional (2D) films, in particular graphene [1][2][3][4][5][6][7][8][9][10][11], and other films of honeycomb symmetry such as so-called hexagonal boron nitride or hBN (which actually forms a honeycomb structure) [12][13][14][15][16][17][18][19] and MoS 2 [20][21][22]. These systems typically show 2D moiré patterns that are defined by a triangular (honeycomb) array of commensurate regions when grown on a substrate with an adsorption surface potential having a triangular (honeycomb) array of minima.…”

“…These different classes of adsorption systems will be referred to as HH, HT, TH, and TT, respectively, where the latter letter refers to the substrate symmetry. These classes of systems include adsorption systems such as Cu, Ni, or Co on Ru(0001) [23,[26][27][28], Ni on Rh(111), Co on Pd(111), Cu on Pd(111) [29][30][31], and Ag on Cu(111) [32][33][34][35][36][37][38] or Ni(111) [39], graphene on a wide variety of metallic (111) substrates [1][2][3][4][5][6][7][8][9][10][11], hexagonal boron nitride grown on Ir(111) [12], Cu(111) [13][14][15], Rh(111) [16][17][18], and Ru(0001) [19]. 2469-9950/2017/96(19)/195439 (16) 195439-1 ©2017 American Physical Society…”

Epitaxial hexagonal boron nitride on Ir(111): A work function template

“…Another area of interest in h-BN are the so-called boron nitride nanomeshesepitaxial monolayers of h-BN grown on transition metal surfaces [4,5]. Various studies have been motivated by their ability to act as a template for bottom-up fabrication techniques, while simultaneously providing electronic decoupling from the metallic substrate [4,[6][7][8][9][10][11][12][13]. The term "nanomesh" highlights the peculiar structure of the h-BN monolayers: Due to the lattice mismatch with the underlying substrate, the atomic registry between the boron and nitrogen atoms and the metallic surface is periodically modulated, resulting in a moiré pattern formed by regions of stronger h-BN/metal and weaker h-BN/metal interaction.…”

Giant Hysteresis of Single‐Molecule Magnets Adsorbed on a Nonmagnetic Insulator

“…This is attributed to magnetic interactions between the molecules. [ 21 ] In addition to MgO, we also investigated hexagonal boron nitride ( h -BN) [ 28 ] as a tunnel barrier. The hysteresis opening on h -BN is wider than the one reported for most surface-adsorbed TbPc 2 (Supporting Information), however, it is signifi cantly narrower than on the MgO thin fi lm.…”