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O: Fachverband Oberflächenphysik

O 6: Poster Session I: Organic molecules on inorganic substrates: Adsorption and growth I

O 6.1: Poster

Montag, 1. März 2021, 10:30–12:30, P

Graphene as an effective template for tuning the structural and electronic properties of organic-inorganic interfaces — •Qiankun Wang, Brian D. Baker Cortés, Joris de la Rie, Mihaela Enache, and Meike Stöhr — Zernike Institute for Advanced Materials, University of Groningen, The Netherlands

Controlling the morphological and electronic properties of organic-inorganic interfaces is essential for achieving efficient interface charge injection (or extraction) and transport properties in for example (opto)electronic devices. Here, we present a combined scanning tunneling microscopy and photoelectron spectroscopy study on the adsorption of 5,10,15,20-tetra(4-pyridyl)porphyrin (H2TPyP) on Cu(111) and graphene/Cu(111), respectively. Our experiments showed that for submonolayer coverage, H2TPyP does not form ordered 2D arrangements on Cu(111). Instead, the molecules adsorb randomly and adopt a saddle-shape configuration. However, annealing at 430 K results in short-range, ordered linear and triangular supramolecular arrangements stabilized by Cu-coordination. In contrast, for H2TPyP on graphene/Cu(111) a self-assembled 2D network stabilized by H-bonding forms with unit cell dimensions a = 2.7 nm, b = 1.2 nm and angle = 78°. Furthermore, the work function increases from 3.8 eV for H2TPyP/Cu(111) to 4.1 eV for H2TPyP/graphene/Cu(111), resulting in a considerably different energy level alignment at the hybrid interface. Our experiments demonstrate the feasibility of tuning organic-inorganic interface properties by employing graphene as an intermediate layer.