Kinetics and electrochemical transistor performance in pgBTTT polymers through ethylene glycol side chain modification and blending techniques

Kaishuai Zhang^a, Lize Bynens^b

^aUniversity of Bern, Freiestrasse 3, Bern, Switzerland

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

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

Oral, Kaishuai Zhang, presentation 137
Publication date: 28th August 2024

The advancement of electrochemical device technology is intricately linked to the structural nuances of polymers. This comprehensive research investigates the influence of ethylene glycol side chains on the performance characteristics of pgBTTT, a regiochemically defined organic electrochemical transistor. A series of pgBTTT polymers were synthesized with varying concentrations of hydrophilic ethylene glycol side chains, ranging from 50% to 100%. The outcomes of this study indicate a significant positive correlation between the proportion of ethylene glycol side chains and the volumetric capacitance of these polymers, with a notable deviation at a 90% side chain concentration.[1] [2]

Building on these findings, the study delved into the realm of blending methodologies as a strategy to further enhance the volumetric capacitance of pgBTTT polymers. Two distinct blending techniques were employed: one involving a blend of pgBTTT with pBTTT(OR)₂, and another comprising a blend of pgBTTT with pgBTTT-OEG-OR. The blend incorporating pBTTT(OR)₂ exhibited a volumetric capacitance that aligned with the trends observed in varying side chain percentages. Contrastingly, the blend with pgBTTT-OEG-OR demonstrated a consistent volumetric capacitance across various ratios.[3] Both blending strategies yielded superior volumetric capacitance compared to the copolymers, particularly at a concentration of 90% ethylene glycol side chains.[4]

A pivotal aspect of this research involved assessing the impact of these blending techniques on the kinetics of the doping and dedoping processes. This inquiry revealed that blends, especially those with matching side chain ratios, displayed markedly improved kinetic efficiency in both doping and dedoping procedures.[5] This discovery opens new pathways for enhancing the performance and efficiency of organic electrochemical transistors and mixed conductors.

In conclusion, the study provides critical insights into the manipulation of polymer structures, specifically through the adjustment of ethylene glycol side chains and strategic blending. These modifications are key to advancing the design and functionality of high-performance electrochemical devices. The findings serve as a valuable foundation for future endeavors in optimizing organic electrochemical transistors and mixed conductors for enhanced efficiency and kinetics.

References:

[1] Flagg, L. Q.; Bischak, C. G.; Onorato, J. W.; Rashid, R. B.; Luscombe, C. K.; Ginger, D. S., Polymer Crystallinity Controls Water Uptake in Glycol Side-Chain Polymer Organic Electrochemical Transistors. Journal of the American Chemical Society 2019, 141 (10), 4345-4354.

[2] Savva, A.; Hallani, R.; Cendra, C.; Surgailis, J.; Hidalgo, T. C.; Wustoni, S.; Sheelamanthula, R.; Chen, X.; Kirkus, M.; Savva, A.; Hallani, R.; Cendra, C.; Surgailis, J.; Hidalgo, T. C.; Wustoni, S.; Sheelamanthula, R.; Chen, X.; Kirkus, M.; Giovannitti, A.; Salleo, A.; McCulloch, I.; Inal, S., Balancing Ionic and Electronic Conduction for High-Performance Organic Electrochemical Transistors. Advanced Functional Materials 2020, 30 (11), 1907657.

[3] Barker, M.; Nicolini, T.; Al Yaman, Y.; Thuau, D.; Siscan, O.; Ramachandran, S.; Cloutet, E.; Brochon, C.; Richter, L. J.; Dautel, O. J., Conjugated polymer blends for faster organic mixed conductors. Materials Horizons 2023.

[4] Ohayon, D.; Druet, V.; Inal, S., A guide for the characterization of organic electrochemical transistors and channel materials. Chemical Society Reviews 2023.

[5] Cavassin, P.; Holzer, I.; Tsokkou, D.; Bardagot, O.; Réhault, J.; Banerji, N., Electrochemical Doping in Ordered and Disordered Domains of Organic Mixed Ionic–Electronic Conductors. Advanced Materials 2023, 35 (35), 2300308.

Acknowledgements:

We would like to express our deepest gratitude to Prof. Natalie Banerji for her invaluable guidance, continuous support, and encouragement throughout this study. Her expertise and insights were instrumental in shaping the direction and outcome of this research. We also extend our heartfelt thanks to Dr. Dimitra Tsokkou for her insightful contributions, rigorous discussions, and unwavering assistance, which greatly enhanced the quality of this work. Special thanks to PhD Lize Bynens for her exceptional work on the synthesis of the materials, without which this research would not have been possible. This research was generously funded by the Swiss National Science Foundation (SNF), whose support we gratefully acknowledge.

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