Copolymers of Diketopyrrolopyrrole and Benzothiadiazole: Design and Function from Simulations with Experimental Support

Deyan Raychev, René Daniel Méndez López, Anton Kiriy, Gotthard Seifert, Jens Uwe Sommer, Olga Guskova

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Alternating block copolymers consisting of diketopyrrolopyrrole and benzothiadiazole electron acceptor units linked together via aromatic five-membered donor heterocycles are studied using a combination of computer simulation techniques and experiments. Four copolymers are modeled starting from their monomers to stacked macromolecules: with two different linkers - thiophene or furan, connecting electron-withdrawing core units - and two different alkyl substituents at lactam nitrogens of diketopyrrolopyrrole - linear dodecyl and branched 2-octyldodecyl chains. In our experiments, we aim at characterization of the optical and electrochemical properties of two copolymers with branched side chains differing in the linker, since as the literature survey shows the data published on these copolymers are very sparse. These properties can be easily interpreted and later compared with theoretical predictions. The results of simulations supported by experiments show that monomers of these polymers have very similar electronic and optical properties, and the main difference between them consists in various chain curvature defined by the linker. More curved furan-containing monomers and more stretched thiophene-linked molecules are characterized by different energetics of the stack formation and diverse in charge carrier mobilities. The branching of the side chains affects the planarity of the macromolecules, leads to longer π- π stacking distance and lamellar interval in the ordered arrays of polymers, and defines the stacking patterns of the conjugated backbones. The ambipolar transport is predicted for the majority of considered copolymer morphologies, and a quantitatively satisfactory agreement between experiment and computation is achieved.

Original languageEnglish
Pages (from-to)904-914
Number of pages11
JournalMacromolecules
Volume52
Issue number3
DOIs
StatePublished - 12 Feb 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019 American Chemical Society.

Funding

This work is funded by the European Regional Development Fund and the Free State of Saxony via the European Social Fund project 100231947 (Young Investigators Group “Computer Simulations for Materials Design − CoSiMa”). The authors gratefully acknowledge Dr. Hartmut Komber (Leibniz Institute of Polymer Research Dresden) for NMR measurements, Vladyslav Savchenko (service contract within CoSiMa project, DCMS, Technische Universitaẗ Dresden) for data processing using Python and the visualization of the simulation results, and Florian Pump (DCMS, Technische Universitaẗ Dresden) for administrative coordination of the CoSiMa project. We thank the Computing Services of the Leibniz Institute of Polymer Research Dresden and the Center for Information Services and High Performance Computing (Technische Universitaẗ Dresden) for providing CPU time.

FundersFunder number
European Regional Development Fund and the Free State of Saxony
European Social Fund100231947

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