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Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 60: Organic Molecules on Inorganic Substrates IV: Electronic Properties, Excitations, Dynamics

O 60.3: Vortrag

Mittwoch, 3. April 2019, 15:30–15:45, H24

Excited Electron Dynamics in Thiophene-based Polymers — •Tobias Reiker1, Carsten Winter1, Deb Kumar Bhowmick1, Nils Fabian Kleimeier1, Zitong Liu2, Deqing Zhang2, and Helmut Zacharias11Center For Soft Nanoscience, Westfälische Wilhelms-Universität Münster — 2Institute of Chemistry, Chinese Academy of Science, Beijing, China

An internal donor-acceptor system is formed by thiophene polymers coupled with pyrrole chains. Different alkyl side chains can improve the interchain packing and affect the backbone conformation, further they can directly influence the charge transporting behavior. Although OFETs and organic photovoltaic cells have been already successfully utilized, the exact internal dynamics of the system are still under investigation. In this presentation we show the results of a time-dependent photoemission study on the thiophene polymers PDPP4T and DTT on a Si(100) substrate. Occupied electronic levels were analyzed with UPS. The fundamental and third harmonics of a Ti:Sapphire laser system with a time-of-flight spectrometer are utilized for static 2PPE to determine the energetic positions of high lying occupied and intermediate unoccupied states. Dynamic 2PPE is then used to study the electron dynamics of the intermediate states directly in the time domain and shows three distinct electronic lifetimes. Depending on the electron kinetic energy lifetimes of a few hundred femtoseconds, up to 3 ps and a slow channel around 15 ps are observed. After annealing at 180°C an unoccupied state at an exitation energy of 0.40 eV loses its long-lived component.

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