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A foldable smartphone? STIBNITE searched for the perfect semiconductor

Roll-up solar panels, bendable phone displays, or better computer chips… The EU project STIBNITE investigated the next generation of semiconductors, made from organic materials based on carbon, nitrogen, and boron. The project has now concluded. During the Open Science Debate on 1 July, the group will present its findings. Will you be there?

Graphene: a wonder material consisting of just one layer of carbon atoms. Flexible and extremely strong. A promising alternative to silicon, thought the scientists of STIBNITE. Silicon, in fact, is not as flexible and therefore not suitable for new applications like a foldable phone or flexible display screen. Graphene could also contribute to improvements in other areas, such as efficiency and sustainability.

However, there was one small problem, the researchers knew: graphene is not a semiconductor like silicon. And that is precisely a crucial property for use in electronic devices. ‘Graphene actually conducts a bit too well,’ says Professor Irene de Groot of the Leiden Institute of Chemistry, one of the researchers within the European consortium. ‘As chemists, we say that graphene does not have a “bandgap”.’ A bandgap is a sort of energy barrier that determines whether a material can conduct electricity or not. If a material has a large bandgap, it means that it is difficult for electrons to move through the material. The material is then less conductive. Small bandgaps, on the other hand, make materials better at conducting electricity.

To conduct or not to conduct

In electronics applications, semiconductors like silicon are popular precisely because of their ability to control electrical currents. This is due to their band structure, which can have both conducting and non-conducting properties. However, due to the lack of a bandgap, graphene can only conduct. This poses a limitation for certain electronic applications where control over the electrical current is necessary.

'By adding other substances to the graphene, we can change its electrial properties.'

From graphene to semiconductor

To turn graphene into a semiconductor, scientists add other substances to the material. De Groot explains: ‘By adding these “impurities” to the graphene, we can change its electrical properties.’ Boron (B) and nitrogen (N) turn out to be good options. But when you combine graphene with boron nitride (BN), something strange happens: the material separates into small islands of graphene and islands of boron nitride, instead of forming a unified whole. Therefore, the STIBNITE researchers searched for other substances that could be added without creating islands. They investigated the effects of new, organic molecules not just carbon or just boron and nitrogen, but all three simultaneously.

'Only possible because of all these experts working together'

De Groot explains: ‘We collaborated with experts from various specialities within physics and chemistry. Experts in organic synthesis prepared the new organic molecules. Surface scientists used these molecules to create and characterise the materials, and chemical engineers used the materials to develop and test new devices. Only because of this diverse group, we succeeded in developing new materials without the occurrence of material segregation. With these materials, we have even created the first electrical devices!’

Open Science Debat 1 July - Join the discussion!

Open Science Debate - Will you join the discussion? During the Open Science debate, the researchers of STIBNITE will provide a brief overview of the project's results, followed by a panel discussion. The debate is open to anyone interested in the chemistry and physics of new materials needed for new affordable and environmentally friendly products and devices.

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