Dresden 2017 – wissenschaftliches Programm
CPP 59.9: Vortrag
Donnerstag, 23. März 2017, 17:45–18:00, ZEU 222
Asymmetric bodipy end-capped oligomer: A molecular seesaw as a polarization-to-wavelength converter — •Philipp Wilhelm1, Jakob Schedlbauer1, Florian Hinderer2, Sigurd Höger2, Jan Vogelsang1, and John M. Lupton1 — 1Universität Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany — 2Universität Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany
Excitation energy transfer (EET) plays a crucial role for the properties of organic photovoltaic devices. Unfortunately, the microscopic pathways of EET are hard to monitor. We therefore introduce a model system, which consists of a π-conjugated donor oligomer (emitting in the blue wavelength region with λmax=450 nm) and two different acceptor dyes, based on bodipy (boron-dipyrromethene) derivatives and located at each end of the oligomer. One of the bodipy endcap units emits in the green (λmax=515 nm) and the other one in the red (λmax=650 nm) wavelength region. By using this molecule with two competing EET pathways from the oligomer to the asymmetric endcaps, we can learn whether the excitation energy migrates preferentially to the global minimum (i.e. the red dye) or if EET is non-deterministic. By employing single-molecule spectroscopy we can address the following questions: does the EET pathway differ between individual molecules? Is the EET pathway like a "seesaw", dynamically changing between red and green over time? Finally, we looked into the question whether the EET pathway can be influenced externally by changing the polarization of the excitation laser. Indeed, we find that the model system can act as a single-molecule light polarization to wavelength converter.