Photoinduced Electron- and Energy-Transfer in Molecules and Materials

Date

Mar 6, 2019

Time

2:00 PM - 3:00 PM

Speaker

Prof. Dr. Benjamin Dietzek

Affiliation

Leibniz-Institute of Photonic Technology Jena (IPHT) and Group Molecular Photonics University Jena

Language

en

Main Topic

Materialien

Other Topics

Materialien, Physik

Host

Description

Photoinduced electron and energy transfer are immanent to solar-energy-conversion processes. This contribution elucidates on recent examples in our group to study excited state excitation transfer processes in non-conventional samples and settings. On the one hand fluorescence upconversion by triplet-triplet annihilation is demonstrated for a fully polymer-integrated material, i.e. in the limit of restricted diffusion. Organic sensitizer and acceptor are covalently attached to the poly(methacrylate) backbone, yielding a metal-free macromolecular all-in-one system for fluorescence upconversion. A photophysical model taking the heterogeneous local environment within the polymers into account is proposed. On the other hand this contribution will discuss our recent advances in elucidating the properties of electronically excited states in intermediates of multi-electron transfer cascades, which are key to the function of e.g. natural and artificial photosynthesis. It will be reported on experimental developments to combine resonance Raman spectroscopy and ultrafast time-resolved transient absorption spectroscopy with electrochemical methods, in particular cyclovoltammetry and chronoamperometry. Such combination allows us to electrochemically generate molecular species mimicking the intermediates in multi-electron transfer cascades and – subsequently – characterize their excited-state properties spectroscopically. The talk will focus on two scientific examples, one concerning the oxidative spectroelectro-chemistry of photosensitizers potentially used in dye-sensitized solar cells. The second example addresses the properties reductively generated intermediates of photocatalytic hydrogen evolution reactions relying on Ru(II) complexes and triaryl chromophores as photoactive sensitizer Units.

Links

• Seminars at the IFW

Last modified: Mar 6, 2019, 1:06:56 AM