Hannover 2020 – scientific programme
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MO: Fachverband Molekülphysik
MO 16: Femtosecond Spectroscopy II
MO 16.3: Talk
Thursday, March 12, 2020, 14:30–14:45, f102
Intramolecular Singlet Fission in Tetraaza-TIPS-Pentacene Oligomers: Triplet formation via the Biexcitonic State — •Nicolò Alagna1,2, Jose L.P. Lustres1,2, Nikolaus Wollscheid1,2, Qingqing Luo1, Jie Han3, Andreas Dreuw2,3, Florian Geyer4, Victor Brosius4, Uwe H.F. Bunz4, Tiago Buckup1,2, and Marcus Motzkus1,2 — 1Physikalisch Chemisches Institut, Ruprecht-Karls University, Germany — 2Centre for Advanced Materials, University of Heidelberg, Germany — 3Interdisziplinäres Zentrum für Wissenschaftliches Rechnen, Ruprecht-Karls University, Germany — 4Organisch Chemisches Institut, Ruprecht-Karls University, Germany
Singlet fission (SF) is a photo-induced process where an excited singlet exciton is converted into two triplet states of nearly half energy. It has been shown for several systems in the liquid phase and in thin films. In this work, we investigate SF in diethynylbenzene-linked tetraaza-TIPS-pentacene dimers with different geometry configurations. Analysis of transient absorption and fluorescence measurements shows an efficient SF (ΦT> 160%) in the ortho and meta dimer as well as in the (1,3,5) trimer. Our results show that the formation of the long-lived triplet state T1 takes place via an intermediate component, called the correlated triplet pair or biexcitonic state. The long-lived triplet state T1 formed by SF is, however, only a fraction compared to the total amount of the triplet-pair generated. We show that the 1(TT) state decays via annihilation and triplet fusion mechanisms.