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DS: Fachverband Dünne Schichten

DS 12: Poster

DS 12.41: Poster

Mittwoch, 29. März 2023, 17:00–19:00, P3

Theoretical insights into the monolayer adsorption and characterization of HB238 Merocyanine on Ag(100) surface — •Ritu Tomar, Thomas Bredow, Anna Kny, and Moritz Sokolowski — Clausius Institute of Physical and Theoretical Chemistry, University of Bonn, Germany

Merocyanines (MCs) are intriguing compounds that can be used as efficient absorbers for organic solar cells. We studied the adsorption of HB238 merocyanine on the surface of Ag (100) using STM and SPA-LEED experiments, which suggested that HB238 self-organizes as chiral tetramers upon adsorption. The molecular structure was significantly different from the typical configuration in the bulk phases of HB238. It is critical to control the structure and morphology of merocyanine films to enhance light absorption and optimize their optoelectronic properties. Therefore, we performed quantum chemical calculations to corroborate our experimental findings. Initially, we screened the HB238 conformers and used the most stable structure to determine the optimal adsorption orientation of HB238 on the Ag surface using the semi-empirical method GFN1-XTB in DFTB+. HB238 preferentially adheres face-on to the Ag surface. Next, we optimized the tetramer models at the DFT level to analyze the assembly of chiral tetramers while maintaining supercell lattice constant values, as in the experiment. We then relaxed the HB238 molecules on the Ag 3-layer slab model and fixed the bottom two layers using the GGA method in VASP. However, rapid and effective system convergence was achieved only using the ASE/LBFGS optimization algorithm.