Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 31: Poster: Organic Molecules on Inorganic Substrates

O 31.6: Poster

Dienstag, 19. März 2024, 18:00–20:00, Poster C

LEEM/PEEM study of F₁₆CuPc/p-6P organic thin films on SiO₂ — •Franz Niklas Knoop, Klaus Stallberg, and Winfried Daum — Institute of Energy Research and Physical Technologies, TU Clausthal, Germany

Systematic investigations of the influence of molecular order on the charge-carrier dynamics in organic semiconductors require well-defined and controllable model systems. While single-crystalline metal surfaces are suitable substrates for the epitaxial growth of long-range ordered organic layers, strong molecule-metal interaction also modifies the carrier dynamics in the layer. In contrast, organic thin films on weakly interacting substrates such as SiO₂ exhibit only poor structural order in general.

Here, we present a low-energy electron microscopy (LEEM) study of the structure of thin copper-hexadecafluorophthalocyanine (F₁₆CuPc) films, which were deposited on the native oxide of Si(100) substrates after precovering of the surface with a monolayer of para-sexyphenyl (p-6p) molecules. The in vacuo thermally evaporated p-6P layer comprises crystalline domains of upright standing molecules. F₁₆CuPc films deposited on p-6p precovered substrates exhibit µm-sized, well-ordered domains. In contrast, only nm-sized domains are formed if F₁₆CuPc is deposited directly on the native oxide. Structural investigations with µLEED and AFM are combined with polarization-dependent two-photon photoemission electron microscopy (2P-PEEM) to reveal the influence of molecular order on optical excitations in the F₁₆CuPc film.

Keywords: LEEM; PEEM; Organic heterostructures; Phthalocyanines; Organic thin films