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O: Fachverband Oberflächenphysik

O 32: Poster Session - Organic Molecules on Inorganic Substrates: Adsorption and Growth

O 32.9: Poster

Montag, 16. März 2020, 18:15–20:00, P1C

A highly ordered commensurate structure of merocyanine tetramers on Ag(100): STM- and SPA-LEED-investigations — •Anna J. Kny¹, Niklas Humberg¹, Dirk Hertel², Klaus Meerholz², and Moritz Sokolowski¹ — ¹Institut für Physikalische und Theoretische Chemie der Universität Bonn, Germany — ²Department Chemie, Universität zu Köln, Germany

Vacuum deposited films of the merocyanine molecule 2-[5-(5-dibutylamino-thiophen-2-yl-methylene)-4-tert-butyl-5H-thiazol-2-ylidene]-malononitrile (HB238) have been investigated in the context of organic solar cells [1]. Although the specific structural order in these films is important for photovoltaic properties, only very little is known about the adsorption, ordering and film growth of this molecule on surfaces. Therefore, we investigated monolayers of HB238 on a Ag(100) surface by SPA-LEED and STM.
When HB238 is deposited onto the Ag(100) at room temperature and then cooled down immediately to 34 K, the formation of two different phases can be observed. Directly after growth, a phase with chain-like aggregates and only short-range order prevails. Upon annealing at 68 K, it transforms into a second highly ordered phase with a commensurate superstructure. This phase is composed of homochiral tetramers of HB238 molecules. The thiophene and thiazole units are bonded to the Ag(100) surface yielding a flat lying molecular orientation. Upon further annealing dewetting and cluster formation occurs.
[1] JACS 137 (2015) 13524.