Molecular Arrangements in the First Monolayer of Cu-Phthalocyanine on In$_2$O$_3$(111)

Matthias Blatnik; Fabio Calcinelli; Andreas Jeindl; Moritz Eder; Michael Schmid; Jan Čechal; Ulrike Diebold; Peter Jacobson Oliver T. Hofmann; Margareta Wagner

doi:10.1039/D5TC01394A

paper

Molecular Arrangements in the First Monolayer of Cu-Phthalocyanine on In $_{2}$ O $_{3}$ (111)

arXiv:2507.09044 · doi:10.1039/D5TC01394A

Abstract

Well-ordered organic molecular layers on oxide surfaces are key for organic electronics. Using a combination of scanning tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM) we probe the structures of copper phthalocyanine (CuPc) on In $_{2}$ O $_{3}$ , a model for a prototypical transparent conductive oxide (TCO). These scanning-probe images allow the direct determination of the adsorption site and distortions of the molecules, which are corroborated by DFT calculations. Isolated CuPc molecules adsorb in a flat, slightly tilted geometry in three symmetry-equivalent configurations on the stoichiometric In $_{2}$ O $_{3}$ (111) surface. Increasing the coverage leads to densely-packed 1D chains oriented along $⟨ 1 1 ˉ 0 ⟩$ directions, which dissolve into a highly ordered (2 $\times$ 2) superstructure upon increasing the CuPc density to 3/4 per surface unit cell. At a coverage of one CuPc per surface unit cell, a densely packed (1 $\times$ 1) superstructure fully covers the surface. The molecules still assume the same site and orientation as before, but they partially overlap to accommodate the high packing density, leading to a bending of the molecules. These results are compared to the behavior of CoPc on In $_{2}$ O $_{3}$ (111). In summary, we demonstrate that a uniform first layer of metal-phthalocyanine molecules can be realized on the In $_{2}$ O $_{3}$ (111) surface when using the proper metal atom in the molecule.

Molecular Arrangements in the First Monolayer of Cu-Phthalocyanine on In2​O3​(111)

Abstract

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Molecular Arrangements in the First Monolayer of Cu-Phthalocyanine on In $_{2}$ O $_{3}$ (111)