A Novel Chemical Reaction On A Surface Enables The Emergence Of Solitons In π-Conjugated Polymers

• Researchers demonstrate that the design of potentially highly conducting polymers avoiding doping is feasible.
• The novel chemical reaction on a surface reveals that structural parity drives the emergence of solitons in π-conjugated polymers.

π-conjugated polymers are a class of macromolecules featuring an alternation of single and double bonds along their backbone, which enables delocalized π-electrons. Their unique electronic structure makes them highly conductive and very attractive for applications such as solar cells or light-emitting diodes. To enhance their electronic properties, π-conjugated polymers are often doped. However, the structure and stability of the polymer suffers.

In a new study, researchers introduce an unprecedented reaction, coined indenyl coupling, to design highly conducting carbon-based polymers. They demonstrated the possibility to bond indane-based monomers in an extremely selective and efficient way on a metallic surface affording the design of π-conjugated polymers. Remarkably, the researchers exploited the structural parity of the polymers to afford the emergence of in-gap soliton states, which spatially extend several nanometers along the longitudinal backbone.

The results, recently published in Nature Synthesis, answer a fundamental question in materials science: Is it possible to experimentally synthetize potentially highly conducting polymers without the need of external doping? The authors demonstrate that theoretical predicted concepts of structural parity can be an essential factor to consider when designing tailored nanomaterials hosting topological quasiparticles. This approach could lead to more efficient, cost-effective, and sustainable electronic devices featuring 1D wires.

This work is the result of a collaboration between physicists and chemists at the Madrid Institute for Advanced Studies in Nanoscience (IMDEA Nanociencia), Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Universidade de Santiago de Compostela, the Institute of Physics of the Czech Academy of Science and Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC) and is partially funded by the accreditation Excellence Severo Ochoa awarded to IMDEA Nanociencia (CEX2020-001039-S) and by the accreditation Centro de Investigación de Galicia awarded to CiQUS (ED431G 2019/03).