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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 36: Organic Electronics and Photovoltaics III
CPP 36.12: Talk
Thursday, March 21, 2024, 12:45–13:00, H 0110
Directed exciton transport highways in organic semiconductors — Kai Müller1,2, Sebastian Schellhammer1,3, Nico Gräßler3,4, Bipasha Debnath4, Fupin Liu4, Yulia Krupskaya4, Karl Leo3, Martin Knupfer4, and •Frank Ortmann1,5 — 1cfaed, TU Dresden — 2Institut für Theoretische Physik, TU Dresden — 3IAPP and IAP, TU Dresden — 4Leibniz Institute for Solid State and Materials Research Dresden — 5TUM School of Natural Sciences, Technische Universität München
Exciton bandwidths and exciton transport are difficult to control by material design. We showcase the intriguing excitonic properties in an organic semiconductor material with specifically tailored functional groups, in which extremely broad exciton bands in the near-infrared-visible part of the electromagnetic spectrum are observed by electron energy loss spectroscopy and theoretically explained by a close contact between tightly packing molecules and by their strong interactions. This is induced by the donor-acceptor type molecular structure and its resulting crystal packing, which induces a remarkable anisotropy that should lead to a strongly directed transport of excitons. The observations and detailed understanding of the results yield blueprints for the design of molecular structures in which similar molecular features might be used to further explore the tunability of excitonic bands and pave a way for organic materials with strongly enhanced transport and built-in control of the propagation direction.
Keywords: exciton; H-aggregation; density functional theory; electron energy loss spectroscopy