Berlin 2024 – scientific programme

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O: Fachverband Oberflächenphysik

O 15: Organic Molecules on Inorganic Substrates II: Electronic, Optical and other Properties

O 15.5: Talk

Monday, March 18, 2024, 16:00–16:15, MA 043

Integer Charge Transfer at an Organic–2D Material Interface: PTCDA on h-BN/Ni(111) — •Maximilian Schaal¹, Anu Baby^2,3, Marco Gruenewald¹, Felix Otto¹, Roman Forker¹, Guido Fratesi⁴, and Torsten Fritz¹ — ¹Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany — ²Department of Materials Science, University of Milano-Bicocca, Via R. Cozzi 55, 20125 Milano, Italy — ³STMicroelectronics, Via Tolomeo 1, 20010 Cornaredo, Italy — ⁴ETSF and Dipartimento di Fisica "Aldo Pontremoli", Università degli Studi di Milano, Via Celoria, 16, 20133 Milano, Italy

Weakly interacting systems such as organic molecules on monolayers of hexagonal boron nitride (h-BN) offer the possibility of integer charge transfer leading to the formation of organic ions. Such systems exhibit unique optical and electronic properties which differ from their neutral counterparts. In this study, we used a joint experimental and theoretical approach to investigate the charge transfer of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) molecules on h-BN/Ni(111) by using in-situ differential reflectance spectroscopy (DRS), scanning tunneling spectroscopy (STS) and photoelectron orbital tomography (POT) measurements in combination with density functional theory (DFT) calculations. Our results show that the PTCDA monolayer consists of highly-ordered organic radical anions and neutral molecules. In addition, the occurrence of the integer charge transfer is discussed based on the energy-level alignment.

Keywords: single integer charge transfer; energy-level alignment; perylenetetracarboxylic dianhydride (PTCDA); 2D hexagonal boron nitride (2D h-BN); highly-ordered lateral structure