Jahn-Teller-like Distortion in a One-dimensional π-Conjugated Polymer

Fuente: arXiv
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Main Authors: Wang, Ziyi, Qie, Boyu, Tang, Weichen, Jiang, Jingwei, Liu, Fujia, Jacobse, Peter H., Lu, Jiaming, Li, Xinheng, Louie, Steven G., Fischer, Felix R., Crommie, Michael F.
Format: Preprint
Published: 2025
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author Wang, Ziyi
Qie, Boyu
Tang, Weichen
Jiang, Jingwei
Liu, Fujia
Jacobse, Peter H.
Lu, Jiaming
Li, Xinheng
Louie, Steven G.
Fischer, Felix R.
Crommie, Michael F.
author_facet Wang, Ziyi
Qie, Boyu
Tang, Weichen
Jiang, Jingwei
Liu, Fujia
Jacobse, Peter H.
Lu, Jiaming
Li, Xinheng
Louie, Steven G.
Fischer, Felix R.
Crommie, Michael F.
contents Structurally distorting low-dimensional π-conjugated systems can profoundly influence their electronic properties, but controlling such behavior in extended-width systems remains challenging. Here we demonstrate that a one-dimensional conjugated polymer, poly-(difluorenoheptalene-ethynylene) (PDFHE), undergoes a pronounced out-of-plane backbone distortion, equivalent to a spontaneous symmetry breaking (SSB) of its mirror symmetry. We synthesized PDFHE on noble metal surfaces and characterized its structure and electronic states using low-temperature scanning tunneling microscopy. Rather than adopting a planar, high-symmetry conformation, PDFHE relaxes into non-planar isomers stabilized by a Jahn-Teller-like mechanism that relieves an electronic instability relative to the gapped planar structure. Density functional theory calculations corroborate these findings, revealing that distortion lowers the total polymer energy and enlarges the bandgap, providing a microscopic explanation for the SSB. Our results show that even in mechanically robust extended π-systems, subtle electron-lattice coupling can spontaneously drive significant structural rearrangements.
format Preprint
id arxiv_https___arxiv_org_abs_2508_14416
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Jahn-Teller-like Distortion in a One-dimensional π-Conjugated Polymer
Wang, Ziyi
Qie, Boyu
Tang, Weichen
Jiang, Jingwei
Liu, Fujia
Jacobse, Peter H.
Lu, Jiaming
Li, Xinheng
Louie, Steven G.
Fischer, Felix R.
Crommie, Michael F.
Mesoscale and Nanoscale Physics
Materials Science
Structurally distorting low-dimensional π-conjugated systems can profoundly influence their electronic properties, but controlling such behavior in extended-width systems remains challenging. Here we demonstrate that a one-dimensional conjugated polymer, poly-(difluorenoheptalene-ethynylene) (PDFHE), undergoes a pronounced out-of-plane backbone distortion, equivalent to a spontaneous symmetry breaking (SSB) of its mirror symmetry. We synthesized PDFHE on noble metal surfaces and characterized its structure and electronic states using low-temperature scanning tunneling microscopy. Rather than adopting a planar, high-symmetry conformation, PDFHE relaxes into non-planar isomers stabilized by a Jahn-Teller-like mechanism that relieves an electronic instability relative to the gapped planar structure. Density functional theory calculations corroborate these findings, revealing that distortion lowers the total polymer energy and enlarges the bandgap, providing a microscopic explanation for the SSB. Our results show that even in mechanically robust extended π-systems, subtle electron-lattice coupling can spontaneously drive significant structural rearrangements.
title Jahn-Teller-like Distortion in a One-dimensional π-Conjugated Polymer
topic Mesoscale and Nanoscale Physics
Materials Science
url https://arxiv.org/abs/2508.14416