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Tailoring topological order and π-conjugation to engineer quasi-metallic polymers


Topological band theory predicts that a topological electronic phase transition between two insulators must proceed via closure of the electronic gap. Here, we use this transition to circumvent the instability of metallic phases in π-conjugated one-dimensional (1D) polymers. By means of density functional theory, tight-binding and GW calculations, we predict polymers near the topological transition from a trivial to a non-trivial quantum phase. We then use on-surface synthesis with custom-designed precursors to make polymers consisting of 1D linearly bridged acene moieties, which feature narrow bandgaps and in-gap zero-energy edge states when in the topologically non-trivial phase close to the topological transition point. We also reveal the fundamental connection between topological classes and resonant forms of 1D π-conjugated polymers.

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Fig. 1: Topological quantum phase transition in the acene polymer family.
Fig. 2: Experimental and theoretical results for anthracene (n = 3) polymer.
Fig. 3: Experimental and theoretical results for pentacene (n = 5) polymer.
Fig. 4: Experimental and theoretical results for topologically non-trivial bisanthene polymers.

Data availability

The data for the tight-binding calculation as presented in Fig. 1, as well as STS and DFT DOS data as presented in Figs. 2, 3 and 4 are available as source data. Other data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

Code availability

The tight-binding calculations have been performed using a custom-made code on the Wave Metrics IGOR Pro platform. Details of this tight-binding code can be obtained from the corresponding author upon reasonable request.


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This work was supported by the ERC Consolidator Grant ELECNANO (no. 766555), the EC FP7-PEOPLE-2011-COFUND AMAROUT II, the Spanish Ramón y Cajal programme (no. RYC-2012-11133), the Spanish Ministerio de Economía y Competitividad (projects FIS 2013-40667-P and FIS 2015-67287-P) and the Comunidad de Madrid (projects QUIMTRONIC-CM (Y2018/NMT-4783), MAD2D (S2013/MIT-3007), NANOFRONTMAG (S2013/MT-2850) and PHOTOCARBON (S2013/MIT-2841)). We also acknowledge support from the European Research Council (ERC-320441-Chirallcarbon) and the MINECO of Spain (projects CTQ2017-83531-R and CTQ2016-81911-REDT). IMDEA Nanociencia thanks support from the Severo Ochoa Programme for Centers of Excellence in R&D (MINECO, grant SEV-2016-0686). We also acknowledge support of MEYS CR LM2018110, GACR 18-09914S and Operational Programme Research, Development and Education financed by European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports (project no. CZ.02.1.01/0.0/0.0/16_019/0000754). P.J. acknowledges support from Praemium Academie of the Academy of Science of the Czech Republic. S.E. and B.M. are grateful for support from the Internal Student Grant of Palacký University Olomouc in Olomouc, Czech Republic (project no. IGA_PrF_2019_026). P.J. and S.E. acknowledge access to computing and storage facilities owned by parties and projects contributing to the Czech National Grid Infrastructure MetaCentrum provided under the programme Projects of Large Research, Development, and Innovations Infrastructures (CESNET LM2015042).

Author information




P.J., N.M. and D.E. conceived and designed the experiments. O.G., P.J., N.M. and D.E. supervised the project and led the collaboration efforts. B.C., A.S.-G., B.T. and D.E. carried out the experiments and obtained the data. J.S., E.R.-S. and N.M. synthesized the precursors. The experimental data were analysed by B.C., A.S.-G., B.T., B.M., R.Z., R.M., O.G., P.J. and D.E., and discussed by all the authors. S.E. and P.J. performed the DFT and GW calculations. O.G. carried out the tight-binding calculations. The manuscript was written by B.C., O.G., P.J., N.M. and D.E., with contributions from all the authors.

Corresponding authors

Correspondence to Oliver Gröning or Pavel Jelínek or Nazario Martín or David Ecija.

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The authors declare no competing interests.

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Peer review information Nature Nanotechnology thanks Martina Corso, Giovanni Costantini and Oleg Yazyev for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Tables 1–3, Figs. 1–23, Notes 1–9 and refs. 1–9.

Source data

Source Data Fig. 1

This file contains the data of the tight-binding calculations in panel b

Source Data Fig. 2

This file contains unprocessed STS graphs and DFT density of states plots related to anthracene polymers

Source Data Fig. 3

This file contains unprocessed STS graphs and DFT density of states plots related to pentacene polymers

Source Data Fig. 4

This file contains unprocessed STS graphs and DFT density of states plots related to bisanthracene polymers

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Cirera, B., Sánchez-Grande, A., de la Torre, B. et al. Tailoring topological order and π-conjugation to engineer quasi-metallic polymers. Nat. Nanotechnol. 15, 437–443 (2020).

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