Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 44: Poster: Oxide and Insulator surfaces: Structure, Epitaxy, Growth and Adsorption

O 44.5: Poster

Dienstag, 13. März 2018, 18:15–20:30, Poster A

The Growth and Fluorescence of Phthalocyanine Monolayers and Thin Films on Hexagonal Boron Nitride — •Manal Alkhamisi, Vladimir Korolkov, and Peter Beton — School of Physics & Astronomy, University of Nottingham, Nottingham NG7 2RD, U.K.

We have investigated the adsorption of metal-free phthalocyanine (Pc) thin films on hexagonal boron nitride (hBN) using high resolution atomic force microscopy under ambient conditions. The Pc molecules are sublimed onto hBN under vacuum conditions. A set of samples were grown at room temperature with wide range of film thickness (0.2nm-32nm) and the effect of temperature variation of the substrate was also investigated. At low coverage, metal-free phthalocyanine form needle-like islands in which the molecules are coplanar with the substrate. With increasing thickness in the range 4nm to 32nm the morphology of the islands changed to form dendritic-like disordered islands which are attributed to cofacial stacking of molecules. At growth temperatures close ~100 oC we observe the formation of large monolayer islands and we are able to obtain AFM images with molecular resolution from which we can identify the packing and ordering of the molecules. The photoluminescence of the Pc films was measured with a fluorescence microscope and we find a very intense red-shifted zero-phonon peak for the monolayers with additional peaks for multilayer samples which appear at lower energy and are close to those observed for Pc powder. We discuss these red shifts in relation to substrate and intermolecular interactions.