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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 71: Organic Electronics and Photovoltaics - OLEDs and Molecular Excitations

CPP 71.8: Talk

Thursday, March 15, 2018, 17:00–17:15, C 243

Conical intersection dynamics mediating coherent ultrafast singlet fission — •Hong-Guang Duan^1,2,3, Ajay Jha¹, Vandana Tiwari¹, Pabitra Nayak⁴, Zheng Li¹, Michael Thorwart^2,3, and R. J. Dwayne Miller^1,3,5 — ¹MPSD, Hamburg, Germany — ²I. Institut für Theoretische Physik, UH, Germany — ³CUI, Hamburg, Germany — ⁴University of Oxford, UK — ⁵University of Toronto, Canada

Carrier multiplication in organic semiconductors by singlet fission holds the key to break the Shockley-Queisser limit. Primary step of singlet fission process is a spin-allowed transition of a singlet exciton to a doubly excited pair of spin-correlated triplets. Consequently, two triplets are formed after the spin decoherence. Despite enormous studies, the mechanism of the primary step is still unclear. Here, we use transient grating spectroscopy to probe the vibrational dynamics of singlet fission process in pentacene thin films. Our observations guide us to propose the existence of the conical intersection mediating singlet state and spin-correlated triplet pair transition. The interplay of vibrational modes mediating this transition will be discussed.