Two members from CICECO / University of Aveiro (UA), the researcher Manuel Melle-Franco and the post-doctoral fellow Karol Strutyński, integrate the international team that chemically synthesized a Graphene nanoribbon with of 7.7 nanometers in length, the largest reported to date with atomic precision. The work was published in the prestigious journal Angewandte Chemie.

The team, led by Aurelio Mateo-Alonso of the University of the Basque Country, integrates researchers from CICECO and from the University of Osaka, Japan, has developed a new methodology for the creation of Graphene nanoribbons with almost 8 nm in length.

These are quasi-unidimensional carbon structures, with high application potential in the fields of electronics, photonics, and energy conversion, among others, thanks to their electronic, optical and mechanical properties.

Those properties rely heavily on the Nano dimensions of these fragments of Graphene, such as width and length. It is therefore essential to achieve a high control of the synthesis and an adequate characterization of its properties. This is done through organic synthesis methods with atomic precision, but until now, only allowed for the development of smaller chains.

In this study, a new approach to the synthesis of Graphene Nanoribbons was developed, through a series of iterative reactions of unprotection and condensation. This process was demonstrated through the synthesis and characterization of three nanoribbons containing 10, 20 and 30 conjugated linearly-fused aromatic rings with lengths of 2.9, 5.3, and 7.7 nm, respectively. The last one, the longest graphene nanoribbon reported to date with atomic precision. Characterization was performed by nuclear magnetic resonance spectroscopy and using computer models developed in Aveiro, in the group led by Manuel Melle-Franco, enabling also to rationalize the electronic and optical properties. 

New technology of flexible printable circuits

Research undertaken, in addition to allowing the synthesizes of the longest nanoribbon so far, paves the way for the synthesis of larger chains, to validate properties predicted theoretically, and to the use of these properties in applications such as field-effect transistors, photodetectors, solar cells and molecular wires.

The work, published in the prestigious journal Angewandte Chemie [1], is the result of the project 2D-INK, funded by the EU with EUR 3 million, in the area of "Future and emerging Technologies". 2D-INK aims to lay the foundations for a new flexible and printable circuits technology, with nanoribbons based inks, or with materials such as "pitted graphene", fruit of this same project and presented recently in Angewandte Chemie [2].

When being intended for printable circuits, these structures are designed from scratch to be soluble and have electronic properties suitable for this purpose. In fact, the presence of holes or the reduced width of the nanoribbons allows Graphene to develop semiconductor properties, a fundamental property to be able to function in a circuit. Study and synthesis of these materials are very complex, and it is essential to use computational models, such as those developed at CICECO, to allow studying virtually any material and to rationalize or predict their properties before entering the lab.

[1] Cortizo-Lacalle, D; Mora-Fuentes, JP; Strutynski, K; Saeki, A; Melle-Franco, M; Mateo-Alonso, A (2018) Monodisperse N-Doped Graphene Nanoribbons Reaching 7.7 Nanometers in Length. ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 57, 3, 703-708. DOI: 10.1002/anie.201710467

[2] Marco, AB; Cortizo-Lacalle, D; Perez-Miqueo, I; Valenti, G; Boni, A; Plas, J; Strutynski, K; De Feyter, S; Paolucci, F; Montes, M; Khlobystov, AN; Melle-Franco, M; Mateo-Alonso, A (2017) Twisted Aromatic Frameworks: Readily Exfoliable and Solution-Processable Two-Dimensional Conjugated Microporous Polymers. ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 56, 24, 6946-6951. DOI: 10.1002/anie.201700271