Improving OECT Performance and Reproducibility via Aggregation-Assisted Purification of Conjugated Polymers

Jessica I. Vasquez^a, Ruby S. Raju^a, Arianna Magni^b, Jochen Vanderspikken^a^,^c, Meghna Jha^a, Wouter Maes^c, Alberto Salleo^b, Megan M. Westwood^a, Alexander Giovannitti^a

^aDepartment of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg SE-412 96, Sweden

^bDepartment of Materials Science and Engineering, Stanford University, Stanford, CA, USA;, United States

^cHasselt University, Institute for Materials Research (imo-imomec), Martelarenlaan 42, B-3500 Hasselt, Belgium.

Proceedings of MATSUS Spring 2026 Conference (MATSUSSpring26)

I1 Novel materials and strategies for organic bioelectronics

Barcelona, Spain, 2026 March 23rd - 27th

Organizers: Miryam Criado-Gonzalez, Alberto Scaccabarozzi and Gabriele Tullii

Oral, Jessica I. Vasquez, presentation 616
Publication date: 15th December 2025

In comparison with inorganic semiconductors, organic semiconducting polymers (OSCs) development and commercialization as materials for next-generation bioelectronic devices is limited by batch-to-batch variations and performance differences due to molecular weight effects. Despite OSCs presenting important advantages, such as mechanical flexibility, synthetic tunability, and solution processability, one of the critical challenges is their purity. [1], [2] Impurities left over from synthesis, such as heavy metal ions or low-molecular-weight chains, negatively impact electronic charge transport and long-term stability. When employed in bioelectronic devices, leakage of heavy metal ions left in the polymer can harm biological systems and cells. Traditional purification techniques, such as Soxhlet extraction [3] and metal scavenging [4], are often ineffective in removing chemical side products left over from synthesis, making it difficult to study the intrinsic properties of the materials. Therefore, developing complementary purification techniques to remove these side products is crucial in achieving reproducible and safe bioelectronic devices.

In my talk, I will describe how high-performance liquid chromatography (HPLC) improves the purity of polymeric n-type OSCs. HPLC fractionation allows separation based on hydrodynamic volume, making it possible to narrow the molecular-weight distribution and the selectively remove low-molecular-weight chains as well as metal residues. OSCs based on naphthalene-1,4,5,8-tetracarboxylic-diimide-bithiophene (NDI-T2) achieve improved electronic charge transport properties in organic electrochemical transistors (OECTs) and fewer batch-to-batch variations in device performance and stability.

References:

[1] Paulsen, B.D., Tybrandt, K., Stavrinidou, E. et al. Organic mixed ionic–electronic conductors. Nat. Mater. 2020, 19, 13–26.

[2] Yu, S.; Kousseff, C.; Nielsen, C. n-Type semiconductors for organic electrochemical transistor applications, Synthetic Metals, 2023, Volume 293, 117295.

[3] Liu, J.; Loewe, R. S.; McCullough, R. D. Employing MALDI-MS on Poly(alkylthiophenes): Analysis of Molecular Weights, Molecular Weight Distributions, End-Group Structures, and End-Group Modifications. Macromolecules 1999, 32 (18), 5777– 5785.

[4] Kuwabara, J.; Yasuda T.; Takase N.; Kanbara T. Effects of the Terminal Structure, Purity, and Molecular Weight of an Amorphous Conjugated Polymer on Its Photovoltaic Characteristics, ACS Applied Materials & Interfaces, 2016, 8 (3), 1752-1758.

Acknowledgements:

We thank the ERC project number 10111607 for financial support for this study.

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