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O: Fachverband Oberflächenphysik
O 46: Poster Organic Molecules on Inorganic Substrates: Electronic, Optical and Other Properties
O 46.10: Poster
Dienstag, 18. März 2025, 18:00–20:00, P2
Field driven crossover of bonding and antibonding states in excitonic aggregates — •Amandeep Sagwal1,2, Rodrigo Cezar De Campos Ferreira1,3, Petr Kahan1, Tomáš Neuman1, and Martin Švec1,3 — 1Institute of Physics, Czech Academy of Sciences — 2Faculty of Mathematics and Physics, Charles University; Czech Republic — 3Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences
The present study aims to examine the effect of an electric field on the excitonic states of chromophore aggregates confined in optical nanocavity of a low-temperature SPM. Utilizing an optical configuration intended for near-field spectroscopies, tip-enhanced photoluminescence (TEPL) is used to investigate PTCDA molecules, deposited on a thin decoupling layer of NaCl on Ag(111) surface. A different energy shift is observed consistently between the bonding and antibonding excitonic emission lines in the spectra of dimer, trimer, and tetramer aggregates, in some cases even leading to a crossover. Typically, the antibonding states manifest a larger blue shift with increasing positive bias voltage applied on the gate electrode (substrate). We discuss the phenomenon using TD-DFT simulations and many-body state diagrams.
Keywords: chromophore; excitonic states; nanocavity; TEPL; PTCDA