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Updated: Mar 17, 2026

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
Published on: May 29, 2018
Electronic structure dynamics in a low bandgap polymer studied by time-resolved photoelectron spectroscopy
Ute B Cappel1, Stefan Plogmaker1, Joachim A Terschlüsen1
1Division of Molecular and Condensed Matter Physics, Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden. Ute.cappel@physics.uu.se.
Abstract:
Means to measure the temporal evolution following a photo-excitation in conjugated polymers are a key for the understanding and optimization of their function in applications such as organic solar cells. In this paper we study the electronic structure dynamics by direct pump-probe measurements of the excited electrons in such materials. Specifically, we carried out a time-resolved photoelectron spectroscopy (TRPES) study of the polymer PCPDTBT by combining an extreme ultraviolet (XUV) high harmonic generation source with a time-of-flight spectrometer. After excitation to either the 1st excited state or to a higher excited state, we follow how the electronic structure develops and relaxes on the electron binding energy scale. Specifically, we follow a less than 50 fs relaxation of the higher exited state and a 10 times slower relaxation of the 1st excited state. We corroborate the results using DFT calculations. Our study demonstrates the power of TRPES for studying photo-excited electron energetics and dynamics of solar cell materials.
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