Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 57: Organic Electronics and Photovoltaics IV - Excitonic Properties and Light-Emitting Devices
CPP 57.10: Vortrag
Donnerstag, 4. April 2019, 17:30–17:45, H18
Investigating diffusion controlled singlet fission of a chlorinated phenazinothiadiazole. — •Nikolaus Wollscheid1,3, Nicolo Alagna1, José Luis Perez Lustres1,3, Victor Brosius2, Florian Geyer2, Uwe Bunz2,3, Tiago Buckup1, and Marcus Motzkus1,3 — 1Physikalisch- Chemisches Institut, Ruprecht- Karls-Universität Heidelberg — 2Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg — 3Centre for Advanced Materials, Ruprecht-Karls-Universität Heidelberg
Singlet fission (SF) is a carrier multiplication process where one excited singlet state yields two triplet states upon close interaction of two chromophores. This ultrafast photoreaction was first observed in solid state and has strong implications in organic photovoltaics. In order to disentangle the mechanism by extending the dynamics to longer timescales, concentrated solutions of TIPS-Tetracene were investigated. Here, the reaction is controlled by the diffusion of the reaction partners, which allowed for the isolation of the spectrum of an intermediate excimer state [1]. In this work, we use ultrafast transient absorption spectroscopy to investigate concentrated solutions of a chlorinated phenazinothiadiazole in toluene. The observation of a correlation between singlet decay and triplet formation, combined with the linear dependence of the corresponding decay rate on concentration, indicates diffusion controlled SF. For high concentrations, spectral analysis suggests direct and efficient SF, whereas an additional process is observed for low concentrations.
[1] H. L. Stern et al., PNAS, 112, 7656 (2015).