Conjugated polyions: Polymers with ionic, water-soluble backbones

Thomas Pieter Voortman

Research output: ThesisThesis fully internal (DIV)

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Organic photovoltaics (OPV) is an emerging solar power technology in which the active layer consists of molecules that are built-up mostly from carbon and hydrogen. However, OPV technologies still face major scientific challenges: high performance materials with good synthetic accessibility must be developed, processing solvents must be benign and renewable, and processing conditions must be relatable with large-scale printing.

This thesis presents the development of a new class of semiconducting polymers, conjugated polyions (CPIs) which are robust, semi-conducting polymers bearing closed-shell cationic charges in the conjugated main chain, either transiently or permanently. We synthesize CPIs by converting cross-conjugated aromatic polyketones to linearly-conjugated, cationic polyarylmethines via a process we call “spinless doping”.

We studied the effects of varying combinations of polymer backbones and pendant groups between ionic/hydrophilic and aliphatic/hydrophobic, and compared film morphologies by atomic force microscopy (AFM).We observe a clear trend; conjugated polymers in which the pendant groups and backbone are matched, either ionic–ionic or hydrophobic–hydrophobic, form smooth, structured, homogenous films from water (ionic) or THF (hydrophobic). The fully ionic polymers are CPIs and demonstrate a comparable film morphology with conventional conjugated polymers, comprising hydrophobic backbones and pendant groups. Mis-matched conjugated polymers, by contrast, form inhomogeneous films with rough topologies, with obvious signs of deleterious aggregation and precipitation.

The methods that are developed in this thesis form the groundwork towards a new class of water-processable conjugated polymers. We expect that CPIs will be eventually used to construct OPV devices in a scalable and renewable manner.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Groningen
  • Chiechi, Ryan, Supervisor
  • Hummelen, Kees, Supervisor
  • Herrmann, Andreas, Assessment committee
  • Vanderzande, Dirk J. M., Assessment committee, External person
  • Wudl, F., Assessment committee, External person
Award date28-Jun-2016
Place of Publication[Groningen]
Print ISBNs978-90-367-8934-9
Electronic ISBNs978-90-367-8933-2
Publication statusPublished - 2016

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