Rostock 2019 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 18: Posters 2: Time Resolved Spectroscopy

MO 18.8: Poster

Mittwoch, 13. März 2019, 16:15–18:15, S Foyer LLM

Effect of External Electric Field on Charge-Pair Dynamics in Poly-[3-Hexylthiophene] (P3HT): A Femtosecond Time-Resolved Study — •Debkumar Rana, Patrice Donfack, Vladislav Jovanov, Veit Wagner, and Arnulf Materny — Jacobs University Bremen, Department of Physics & Earth Sciences, Campus Ring 1, 28759, Bremen, Germany

Organic semiconductors have attracted considerable attention in recent years. However, a complete fundamental understanding of the relevant elementary processes is still missing. Several subtle processes such as those involving bound states (e.g. charge-pair states) are crucial to the overall macroscopic picture of device performance based on free charge carriers. In our contribution, we have investigated the dynamics of charge-pair states in Poly-[3-hexylthiophene] (P3HT), a promising organic semiconductor already studied by many researchers, utilizing standard and electric field-dependent transient absorption spectroscopy in order to obtain a realistic picture of the dynamics, since typical devices operate under an applied voltage in practice.

We have found that due to dissociation in the presence of external electric fields, charge-pair recombination time scales and pathways are significantly affected. Especially, our study has revealed a direct observation of different kinds of charge pairs as the result of an applied reverse bias, which we have attributed to typical polaron pairs and loosely bound polaron pairs. These charge pairs have shown completely different dynamics in our study. We will present and discuss our first experimental results.