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Data mining for new organic compounds

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.

The researchers areclooking 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.


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.

“It takes weeks to months to synthesize, test and optimize new materials in the laboratory,” says Prof Karsten Reuter. “Using computational screening, we can accelerate this process immensely.”

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.

Using algorithms, researchers 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.

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.