Graphene-Induced Substrate Decoupling and Ideal Doping of a Self-Assembled Iron-phthalocyanine Single Layer

Abstract

Iron-phthalocyanine molecules self-assemble on the moiré pattern of graphene/Ir(111) as a flat and weakly interacting layer, as determined by core-level photoemission and absorption spectroscopy. The graphene buffer layer decouples the FePc two-dimensional structure from the underlying metal; the electronic structure of the FePc molecular macrocycles is preserved; and the Fe-L2,3 edges present narrower and slightly modified resonances at the FePc single-layer coverage with respect to a thin film. The FePc layer induces a slight electron doping to the Ir-supported graphene resulting in the Dirac cone position expected for an ideal free-standing-like graphene layer with the standard Fermi velocity. © 2012 American Chemical Society

Metal-phthalocyanine ordered layers on Au(110): Metal-dependent adsorption energy

“…The HOMO if is at almost the same energy for both FePc and CoPc SLs and it has been attributed to the macrocycle interaction through the π a 1u orbitals with the Au d states. 6 It is worth noticing that FePc on graphene/Ir does not show a shift in the a 1u molecular orbital, 8 owing to the very low interaction of FePc with the graphene/Ir substrate. The interface I 0 peak lies at 0.21 eV and 0.73 eV eV BE for the FePc-SL and the CoPc-SL, respectively.…”

“…30 The estimated activation energy (2.27 eV) is in very good agreement with the activation energy obtained for MPcs multi-layer desorption from graphene/Ir (2.2-2.4 eV), where the MPc molecules also pile-up face-on onto the graphene surface. 8,36,37 Thus, the TF desorption temperature is independent of the central metal ion, and of the substrate, once the MPc molecules assemble in planar layers.…”

“…4 The presence of a transition metal ion characterized by a different filling of the d orbitals, 5,6 combined with a careful choice of the substrate, strongly influences the properties of the substrate-molecule interface. 7,8 Long-range ordering can be improved by exploiting the patterning of suitable metallic substrates. Ordered assembling can be obtained either by using metal vicinal surfaces as template, [9][10][11] or by depositing the molecules onto naturally patterned surfaces, like the Au(110)-(1×2) reconstructed surface.…”

Effect of Interlayer Coupling on Ultrafast Charge Transfer from Semiconducting Molecules to Mono- and Bilayer Graphene

“…Furthermore, in both BG and SG, there is no significant shift (<0.02 eV) in the position of the graphene σ band with respect to E F after ZnPc deposition [35], implying that the graphene is not significantly doped by ZnPc. For comparison, previous work finds that, when FePc is deposited on graphene, ground-state charge transfer from FePc to graphene causes the Fermi level to shift up only by 0.08 eV [46]. The doping effect of ZnPc is expected to be even less due to the much weaker molecule-substrate interaction compared to that of FePc [47].…”

Surface chemistry of porphyrins and phthalocyanines

“…Graphene and h-BN monolayers between the metal substrate and the adsorbed molecules can lead to a partial electronic decoupling when the metal substrate is weakly interacting, such as Ir(1 1 1) [584,628], whereas substantial residual coupling was observed for more strongly interacting substrates such as Ni(1 1 1) and Ru(0 0 0 1) [582,583,585,[598][599][600]612].…”