Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 31: Ultrafast Electron and Spin Dynamics

MA 31.1: Poster

Dienstag, 21. März 2017, 18:30–20:30, P2-EG

Excited Electron Dynamics in Thiophene-based Polymers — •Carsten Winter, Deb Kumar Bhowmick, Nils Fabian Kleimeier, and Helmut Zacharias — Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster

Optically active thiophene-based polymers are promising candidates for solar cell, OLED or transistor applications. Several variants of thiophene polymers coupled with pyrrole or fluorene chains exist, and form an internal donor-acceptor system.

In this presentation we show the results of a time-dependent photoemission study on the three thiophene polymers PFTT (with a fluorene extension), PDPP4T and DTT (with a pyrrole extension) on a Si(100) substrate. The fundamental, second and third harmonics of a 6 kHz, 35 fs Ti:Sapphire laser system with a time-of-flight spectrometer are utilized for static 3PPE to determine the energetic positions of high lying occupied and intermediate unoccupied electronic levels. Dynamic 3PPE is then used to study the electron dynamics of the intermediate states directly in the time domain.

One-color 3PPE with 3 eV on PFTT shows intermediate lifetimes of 65 to 195 fs depending on the electron kinetic energy and the order of p- and s-pulse. On PDPP4T and DTT a two-color experiment (1.5 eV and 4.5 eV) can determine two distinct, longer electronic lifetimes between 1 and 10 ps for the faster channel and 20 to 100 ps for the slower channel.