Metal–Ligand Based Mechanophores Enhance Both Mechanical Robustness and Electronic Performance of Polymer Semiconductors

Hung Chin Wu, Franziska Lissel, Ging Ji Nathan Wang, David M. Koshy, Shayla Nikzad, Hongping Yan, Jie Xu, Shaochuan Luo, Naoji Matsuhisa, Yuan Cheng, Fan Wang, Baohua Ji, Dechang Li, Wen Chang Chen, Gi Xue, Zhenan Bao

Research output: Contribution to journalArticlepeer-review

Abstract

The backbone of diketopyrrolopyrrole-thiophene-vinylene-thiophene-based polymer semiconductors (PSCs) is modified with pyridine (Py) or bipyridine ligands to complex Fe(II) metal centers, allowing the metal–ligand complexes to act as mechanophores and dynamically crosslink the polymer chains. Mono- and bi-dentate ligands are observed to exhibit different degrees of bond strengths, which subsequently affect the mechanical properties of these Wolf-type-II metallopolymers. The counter ion also plays a crucial role, as it is observed that Py-Fe mechanophores with non-coordinating BPh4 counter ions (Py-FeB) exhibit better thin film ductility with lower elastic modulus, as compared to the coordinating chloro ligands (Py-FeC). Interestingly, besides mechanical robustness, the electrical charge carrier mobility can also be enhanced concurrently when incorporating Py-FeB mechanophores in PSCs. This is a unique observation among stretchable PSCs, especially that most reports to date describe a decreased mobility when the stretchability is improved. Next, it is determined that improvements to both mobility and stretchability are correlated to the solid-state molecular ordering and dynamics of coordination bonds under strain, as elucidated via techniques of grazing-incidence X-ray diffraction and X-ray absorption spectroscopy techniques, respectively. This study provides a viable approach to enhance both the mechanical and the electronic performance of polymer-based soft devices.

Original languageEnglish
Article number2009201
JournalAdvanced Functional Materials
Volume31
Issue number11
DOIs
Publication statusPublished - 2021 Mar 10

Keywords

  • charge transport
  • mechanophore
  • metal-ligand coordination
  • polymer semiconductor
  • stretchable electronics

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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