Regensburg 2022 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 39: Molecular Electronics and Excited State Properties
CPP 39.4: Vortrag
Donnerstag, 8. September 2022, 12:15–12:30, H38
Charge Transfer and Singlet Fission in Pentacene/Acceptor thin films — •Martin Richter1, Christoph Theurer2, Debkumar Rana1,3, Katharina Broch2, and Petra Tegeder1,3 — 1Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 253/229, 69120 Heidelberg, Germany — 2Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany — 3Centre for Advanced Materials, Universität Heidelberg, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
Singlet fission (SF) is a process where a singlet excited state is converted into two triplet excited states. Since SF is exothermic in pentacene (PEN), it is an excellent material to investigate charge transfer (CT) interactions with electron acceptors. Here, stacked bi-layers of PEN either with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) or 2,2'-(perfluoronaphthalene-2,6-diylidene)dimalononitrile (F6-TCNNQ) were investigated with transient absorption spectroscopy. The experiments show formation of triplet pairs, due to the SF process with a slightly slower time constant compared to the pure PEN. Subsequently a separation of the correlated triplet pair can be observed, a process that has been identified also in PEN thin films. A drastic reduction of the triplet lifetime is extracted with both acceptors. Further, evidence for diffusion of excitons to the interface followed by charge formation is found for layers with F4-TCNQ, supported by the shifting of an absorption band, caused by electric fields.