Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 39: Organic Photovoltaics II

CPP 39.4: Vortrag

Mittwoch, 14. März 2018, 10:30–10:45, C 243

Incoherent Pathways of Charge Separation in Organic and Hybrid Solar Cells — •Tobias Seewald, Alexander Grupp, Philipp Ehrenreich, Julian Kalb, Arne Budweg, Lukas Schmidt-Mende, and Daniele Brida — Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany

In this work, we investigate the exciton dissociation dynamics occurring at the donor:acceptor interface in organic and hybrid blends employed in the realization of photovoltaic cells. Fundamental differences in the charge separation process are studied with the organic semiconductor polymer poly(3-hexylthiophene) (P3HT) and either [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) or titanium dioxide (TiO2) acting as the acceptor. By using ultrafast broad-band transient absorption spectroscopy with few-fs temporal resolution, we observe that in both cases the incoherent formation of free charges dominates the charge generation process. From the optical response of the polymer and by tracking the excited-state absorption, we extract pivotal similarities in the incoherent energy pathways that follow the impulsive excitation. On time scales shorter than 200 fs, we observe that the two acceptors display similar dynamics in the exciton delocalization. Significant differences arise only on longer time scales with only an impact on the overall photocarrier generation efficiency.