Ultrafast Dynamics of Electronic Excitations in Single Conjugated Polymer Chains

• Applicant: Professor Dr. Richard Hildner
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry ; Experimental Condensed Matter Physics
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 260342502

The ultrafast transport dynamics of electronic excitations is a key process in the initial steps of solar energy conversion in organic photovoltaic devices based on p-conjugated polymers. However, the electronic structure of this material class, and in particular the ultrafast (sub-picosecond) formation and transport dynamics of electronic excitations is still not entirely clear and controversially discussed. Although these processes can in principle be investigated by conventional ultrafast ensemble spectroscopy, the development of a detailed understanding is hampered by the large structural and electronic heterogeneity of conjugated polymers. In this project we will therefore employ ultrafast single-molecule spectroscopy to study the properties of a prototypical and technologically important system, oligo- and polythiophenes, on a molecular scale. We aim at resolving the femtosecond formation of fundamental electronic excitations as well as their subsequent transport dynamics within single thiophene chains by measurements as a function of the thiophene chain length, their local environment, and the temperature. We want to retrieve the time scales, the relaxation energies, and the relaxation pathways of electronic excitations during their initial formation and localisation. Moreover, we will investigate the various factors that influence the intra-chain energy transport, such as the precise chain conformation, the electronic interactions, as well as the role of and the coupling to the local chain environment. A particular focus will be to resolve potential coherent transport on ultrashort (< 250 fs) time scales and to identify the relevant parameters that impact on the coherence lifetime.

• DFG Programme: Research Grants
• Participating Persons: Professorin Dr. Anna Köhler; Professor Dr. Mukundan Thelakkat