A new chemical model of double-layer graphene with improved semiconductor properties

Our laboratory has been working for some time in collaboration with researchers from the Complutense University of Madrid on a molecular model of a double-layer graphene system capable of controlling rotation, which, in turn, allows us to control conductivity and achieve potentially spectacular semiconducting properties.

The result is a new bilayer graphene molecular model. By designing covalently linked molecular nanographenes, we can simulate the search for the magic angle between graphene-like layers, where semiconductivity is achieved—a key property for, for example, the construction of transistors, which are the basic building blocks of computers. The finding has been published in the scientific journal Nature Chemistry.

In addition, this model, developed at the University of Málaga (UMA) and the Complutense University of Madrid (UCM), enables the formation of ionic bonds between organic molecules—where one atom dominates the other in terms of charge separation—whereas in the vast majority of cases studied in organic molecules to date, a shared or covalent bond is formed. The discovery of a metastable state of matter that persists over time and involves electron transfer is a unique case among carbon-based molecules, that this is a unique example of a ‘quantum-mechanical’ molecule featuring a ‘pre-quantum’ or, if preferred, ‘classical’ electrostatic molecular bond due to its Coulombic nature.

Thus, this research lays the foundations for the creation of artificial molecules capable of mimicking the efficiency of photosynthetic processes—converting light energy into electrostatic energy and subsequently into chemical energy. As a result of electron transfer, the designed nanographene bilayer mimics the biological molecules involved in photosynthesis, potentially enabling the development of tailor-designed artificial photovoltaic applications in the future.

‘Synthesis of zwitterionic open-shell bilayer spironanographenes’ is the result of more than three years of research. In addition to Professor Juan Casado Cordón, the study involved scientists from the Department of Physical Chemistry at the University of Málaga: Samara Medina, who was responsible for the experimental work, and Daniel Aranda, who was in charge of the theoretical modelling of the charge-transfer process. The study also involved international laboratories in Japan and Singapore, as well as researchers from the Complutense University of Madrid, led by Professor Nazario Martín, recipient of the 2020 Enrique Moles National Research Award in Chemical Sciences and Technologies.