SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 62: Poster Session V: Organic molecules on inorganic substrates: electronic, optical and other properties I
O 62.7: Poster
Mittwoch, 3. März 2021, 10:30–12:30, P
Imaging Charge Localization in a Conjugated Oligophenylene — •Laerte Patera1,2, Fabian Queck1, and Jascha Repp1 — 1Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany — 2Department of Chemistry, Technical University of Munich, 85748 Garching, Germany
Polaron formation in conjugated polymers has a major impact on their optical and electronic properties. In polyphenylenes, the molecular conformation is determined by a delicate interplay between electron delocalization and steric effects. Injection of excess charges is expected to increase the degree of conjugation, leading to structural distortions of the chain. Here we investigated at the single-molecule level the role of an excess charge in an individual oligophenylene deposited on sodium chloride films. By combining sub-molecular-resolved atomic force microscopy with redox-state-selective orbital imaging, we characterize both structural and electronical changes occurring upon hole injection. While the neutral molecule exhibits a delocalized frontier orbital, for the cationic radical the excess charge is observed to localize, inducing a partial planarization of the molecule. These results provide direct evidence for self trapping of the excess charge in oligophenylenes, shedding light on the interplay of charge localization and structural distortion.