Frank Ortmann Group News

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illustration of different molecules against a crystal structure
Varying the ratio of 3T molecules (foreground) and 6T molecules (indicated in the background) in the blend allows tuning the gap continuously. Credit: Sebastian Hutsch, Frank Ortmann

What is already established for inorganic semiconductors stays a challenge for their organic counterparts: Tuning the energy gap by blending different semiconducting molecules to optimize device performance. Now, scientists from TU Dresden, in cooperation with researchers at TU Munich, as well as University of Würzburg, HU Berlin, and Ulm University demonstrated how to reach this goal.

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Frank is starting at TU München as Professor for Theoretical Methods in Spectroscopy.

PRESS RELEASE from cfaed @ TU Dresden, March 20, 2020

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Illustration of the generation of charge pairs (excitons), the precursors of free charge carriers in the active layer of an organic solar cell. Credit: M. Panhans

Scientists at TU Dresden and Hasselt University in Belgium investigated the physical causes that limit the efficiency of novel solar cells based on organic molecular materials. Currently, the voltage of such cells is still too low - one reason for their still relatively low efficiencies. In their study, by investigating the vibrations of the molecules in the thin films, the scientists were able to show that very fundamental quantum effects, so-called zero point vibrations, can make a significant contribution to voltage losses. The study has now been published in the journal Nature Communications.

Press Release from 04 July, 2019

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Physicists from the Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and the Center for Advancing Electronics Dresden (cfaed) at the TU Dresden, together with researchers from Tübingen, Potsdam and Mainz were able to demonstrate how electronic energies in organic semiconductor films can be tuned by electrostatic forces. A diverse set of experiments supported by simulations were able to rationalize the effect of specific electrostatic forces exerted by the molecular building blocks on charge carriers. The study was published recently in Nature Communications.

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[Deutsche Version unter "read more"]

Physicists from the Research Cluster Center for Advancing Electronics Dresden (cfaed) of the TU Dresden, together with researchers from Spain, Belgium and Germany, were able to show in a study how electrons behave in their injection into organic semiconductor films. Simulations and experiments clearly identified different transport regimes. The study was published now in Nature Communications.

Lecture series of cfaed, IAPP and IFW researchers on fundamentals of charge carrier transport and related phenomena

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The lecture series Selected Topics on Charge Carrier Transport in Organic Semiconductors starts with lecturers from TU Dresden and the Leibniz Institute for Solid State and Materials Research (IFW Dresden). Frank Ortmann (cfaed) today presents an introduction to Transport in Organic Semiconductors from a theoretical point of view. The aim of this course is to combine the experience of various experts from Dresden in this field and to pass the knowledge on to students and doctoral students.

Results have just been published in the renowned journal "Nature Materials"

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Press picture: Illustration of an organic semiconductor layer (green molecules) with dopant molecule (purple). (C): Sebastian Hutsch, Frank Ortmann

Researchers from the Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and the Center for Advancing Electronics Dresden (cfaed) at TU Dresden, in cooperation with Stanford University (USA) and the Institute for Molecular Science in Okazaki (Japan), have identified the key parameters that influence electrical conductivity in doped organic conductors.

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