Issue 17, 2014

Stabilizing cations in the backbones of conjugated polymers


We synthesized a cross-conjugated polymer containing ketones in the backbone and converted it to a linearly conjugated, cationic polyarylmethine via a process we call “spinless doping” to create a new class of materials, conjugated polyions. This process involves activating the ketones with a Lewis acid and converting them to trivalent cations via the nucleophilic addition of electron-rich aryl moieties. Spinless doping lowers the optical band gap from 3.26 to 1.55 eV while leaving the intrinsic semiconductor properties of the polymer intact. Electrochemical reduction (traditional doping) further decreases the predicted gap to 1.18 eV and introduces radicals to form positive polarons; here, n-doping produces a p-doped polymer in its metallic state. Treatment with a nucleophile (NaOMe) converts the cationic polymer to a neutral, non-conjugated state, allowing the band gap to be tuned chemically, post-polymerization. The synthesis of these materials is carried out entirely without the use of Sn or Pd and relies on scalable Friedel–Crafts chemistry.

Graphical abstract: Stabilizing cations in the backbones of conjugated polymers

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Article information

Article type
08 Nov 2013
14 Jan 2014
First published
16 Jan 2014
This article is Open Access
Creative Commons BY license

J. Mater. Chem. C, 2014,2, 3407-3415

Stabilizing cations in the backbones of conjugated polymers

T. P. Voortman, H. D. de Gier, R. W. A. Havenith and R. C. Chiechi, J. Mater. Chem. C, 2014, 2, 3407 DOI: 10.1039/C3TC32204A

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