Synthetically simple conjugated polymers for organic electrochemical transistors

Licentiate thesis, 2024

The soft and flexible nature of organic materials makes them suitable for the integration into wearable or implantable devices. This paves the way for the development of next-generation bioelectronic systems for e.g. medical diagnostics. Most devices in circuitry can be successfully mimicked by using one or multiple organic electrochemical transistors (OECTs). OECTs leverage the ionic nature of electrolytes in most biological systems, which makes them ideal candidates for bioelectronics.

A series of novel glycolated thieno[3,2-b]thiophene-based semiconducting copolymers is chosen as active materials in OECTs. This series was synthesized via direct arylation polymerization. The synthetic complexity indices (SCIs) of the synthesized compounds are comparable with commercial champion OECT materials, and accordingly the new compounds are deemed suitable for upscaling. The SCI evaluation takes synthetic steps, yield, purification, and hazards into consideration to determine the associated risks and costs for upscaling. Subsequently, the effect of chemical structure, polymer properties, and nanostructure are correlated to the ultimate performance of the materials in OECTs. Evaluation of the OECT figure-of-merit against literature and commercial compounds reveals state-of-the-art performance of the synthesized materials.