Organic semiconductors are lightweight, flexible and easy to manufacture. But they often fail to meet expectations regarding efficiency and stability. Researchers at the Technical University of Munich (TUM) are now deploying data mining approaches to identify promising organic compounds for the electronics of the future.
Producing traditional solar cells made of silicon is very energy intensive. On top of that, they are rigid and brittle. Organic semiconductor materials, on the other hand, are flexible and lightweight. They would be a promising alternative, if only their efficiency and stability were on par with traditional cells.
Both the carbon-based molecular frameworks and the functional groups decisively influence the conductivity of organic semiconductors.
Image: C. Kunkel / TUM
Together with his team, Karsten Reuter, Professor of Theoretical Chemistry at the Technical University of Munich, is looking for novel substances for photovoltaics applications, as well as for displays and light-emitting diodes – OLEDs. The researchers have set their sights on organic compounds that build on frameworks of carbon atoms.
Contenders for the electronics of tomorrow
Depending on their structure and composition, these molecules, and the materials formed from them, display a wide variety of physical properties, providing a host of promising candidates for the electronics of the future.
"To date, a major problem has been tracking them down: It takes weeks to months to synthesize, test and optimize new materials in the laboratory," says Reuter. "Using computational screening, we can accelerate this process immensely."
Computers instead of test tubes
The researcher needs neither test tubes nor Bunsen burners to search for promising organic semiconductors. Using a powerful computer, he and his team analyze existing databases. This virtual search for relationships and patterns is known as data mining.
"Knowing what you are looking for is crucial in data mining,” says PD Dr. Harald Oberhofer, who heads the project. "In our case, it is electrical conductivity. High conductivity ensures, for example, that a lot of current flows in photovoltaic cells when sunlight excites the molecules."
Algorithms identify key parameters
Using his algorithms, he can search for very specific physical parameters: An important one is, for example, the "coupling parameter.” The larger it is, the faster electrons move from one molecule to the next.
A further parameter is the "reorganization energy": It defines how costly it is for a molecule to adapt its structure to the new charge following a charge transfer – the less energy required, the better the conductivity.
The research team analyzed the structural data of 64,000 organic compounds using the algorithms and grouped them into clusters. The result: Both the carbon-based molecular frameworks and the "functional groups", i.e. the compounds attached laterally to the central framework, decisively influence the conductivity.
Identifying molecules using artificial intelligence
The clusters highlight structural frameworks and functional groups that facilitate favorable charge transport, making them particularly suitable for the development of electronic components.
"We can now use this to not only predict the properties of a molecule, but using artificial intelligence we can also design new compounds in which both the structural framework and the functional groups promise very good conductivity," explains Reuter.
The project was funded by the "Solar Technologies go Hybrid" research initiative of the Bavarian State Government and is part of the new Cluster of Excellence e-conversion of the Munich universities funded by the German Research Foundation.
The structural data for the analysis were taken from the Cambridge Structural Database. The conductivity data was generated in sophisticated electronic structure calculations on Super-MUC, the supercomputer of the Leibniz Supercomputing Center in Garching. The new computer-designed molecules will be produced in a laboratory within the Cluster of Excellence e-conversion.
Prof. Dr. Karsten Reuter
Chair of Theoretical Chemistry
Lichtenbergstr. 4, 85747 Garching, Germany
Tel.: +49 89 289 13616
Finding the Right Bricks for Molecular Lego: A Data Mining Approach to Organic Semiconductor Design
Christian Kunkel, Christoph Schober, Johannes T. Margraf, Karsten Reuter, Harald Oberhofer
Chem. Mater. 2019, 31, 3, 969-978 – DOI: 10.1021/acs.chemmater.8b04436
https://www.tum.de/nc/en/about-tum/news/press-releases/detail/article/35249/ Link to the press release
Dr. Ulrich Marsch | Technische Universität München
Blocking the iron transport could stop tuberculosis
02.04.2020 | University of Zurich
Discovery of life in solid rock deep beneath sea may inspire new search for life on Mars
02.04.2020 | University of Tokyo
90 million-year-old forest soil provides unexpected evidence for exceptionally warm climate near the South Pole in the Cretaceous
An international team of researchers led by geoscientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now...
The bacteria that cause tuberculosis need iron to survive. Researchers at the University of Zurich have now solved the first detailed structure of the transport protein responsible for the iron supply. When the iron transport into the bacteria is inhibited, the pathogen can no longer grow. This opens novel ways to develop targeted tuberculosis drugs.
One of the most devastating pathogens that lives inside human cells is Mycobacterium tuberculosis, the bacillus that causes tuberculosis. According to the...
An international team with the participation of Prof. Dr. Michael Kues from the Cluster of Excellence PhoenixD at Leibniz University Hannover has developed a new method for generating quantum-entangled photons in a spectral range of light that was previously inaccessible. The discovery can make the encryption of satellite-based communications much more secure in the future.
A 15-member research team from the UK, Germany and Japan has developed a new method for generating and detecting quantum-entangled photons at a wavelength of...
Together with their colleagues from the University of Würzburg, physicists from the group of Professor Alexander Szameit at the University of Rostock have devised a “funnel” for photons. Their discovery was recently published in the renowned journal Science and holds great promise for novel ultra-sensitive detectors as well as innovative applications in telecommunications and information processing.
The quantum-optical properties of light and its interaction with matter has fascinated the Rostock professor Alexander Szameit since College.
Researchers at the University of Zurich show that different stem cell populations are innervated in distinct ways. Innervation may therefore be crucial for proper tissue regeneration. They also demonstrate that cancer stem cells likewise establish contacts with nerves. Targeting tumour innervation could thus lead to new cancer therapies.
Stem cells can generate a variety of specific tissues and are increasingly used for clinical applications such as the replacement of bone or cartilage....
02.04.2020 | Event News
26.03.2020 | Event News
23.03.2020 | Event News
02.04.2020 | Physics and Astronomy
02.04.2020 | Information Technology
02.04.2020 | Health and Medicine