Impact of homocoupling structural defects on materials and OECT device characteristics

Wouter Maes^a^,^b, Lize Bynens^a^,^b, Jochen Vanderspikken^a^,^b, Arwin Goossens^b^,^c, Koen Vandewal^b^,^c, Laurence Lutsen^b

^aHasselt University, Institute for Materials Research (imo-imomec), Design & Synthesis of Organic Semiconductors (DSOS), Martelarenlaan 42, B-3500 Hasselt, Belgium

^bimec, imo-imomec, Wetenschapspark 1, B-3590 Diepenbeek, Belgium

^cHasselt University, Institute for Materials Research (imo-imomec), Organic Opto-Electronics (OOE), Martelarenlaan 42, B-3500 Hasselt, Belgium

Materials for Sustainable Development Conference (MATSUS)
Proceedings of MATSUS Fall 2024 Conference (MATSUSFall24)

#OMIEC - Understanding Mixed Ionic-Electronic Conductors

Lausanne, Switzerland, 2024 November 12th - 15th

Organizers: Natalie Banerji and Olivier Bardagot

Invited Speaker, Wouter Maes, presentation 019
DOI: https://doi.org/10.29363/nanoge.matsusfall.2024.019
Publication date: 28th August 2024

The true structure of alternating conjugated polymers – the state-of-the-art materials for many organic electronics applications – often deviates from the idealized picture. Homocoupling defects are in fact inherent to the widely used cross-coupling polymerization methods. Nevertheless, many polymers still perform excellently in the envisaged applications, which raises the question if one should really care about these imperfections.

In our recent work, we have looked at the relevance of chemical precision (and lack thereof) in conjugated polymers covering the entire spectrum from the molecular scale, to the micro- and meso-structure, up to the device level. We have identified, visualized, and quantified the different types of polymerization errors for alkoxylated variants of the benchmark (semi)crystalline polymer PBTTT and we have introduced a general strategy to avoid homocoupling.[1] Through a combination of experiments and supported by simulations, we have shown that these coupling defects hinder fullerene intercalation and limit device performance as compared to the homocoupling-free analogue. This clearly demonstrates that structural defects do matter and should be generally avoided, in particular when the geometrical regularity of the polymer is essential.

In this contribution, our most recent efforts on this topic will be discussed, extending from the benchmark PBTTT polymers to the state-of-the-art accumulation-mode p-type OECT channel material pgBTTT.

References:

[1] Vanderspikken, J.; Liu, Z.; Wu, X.; Beckers, O.; Moro, S.; Quill, T. J.; Liu, Q.; Goossens, A.; Marks, A.; Weaver, K.; Hamid, M.; Goderis, B.; Nies, E.; Lemaur, V.; Beljonne, D.; Salleo, A.; Lutsen, L.; Vandewal, K.; Van Mele, B.; Costantini, G.; Van den Brande, N.; Maes, W. On the importance of chemical precision in organic electronics: Fullerene intercalation in perfectly alternating conjugated polymers. Adv. Funct. Mater. 2023, 33, 2309403.

Acknowledgements:

This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement no. 964677 (MITICS). W.M., L.B., A.G., and K.V. thank the FWO Vlaanderen for financial support (WEAVE project G025922N and Ph.D. grants 1S70122N and 1S50822N).

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