A Low-Swelling Polymeric Mixed Conductor Operating in Aqueous Electrolytes

Area of Science:

• Materials Science
• Organic Electronics
• Polymer Chemistry

Background:

• Organic mixed conductors are crucial for energy storage, bioelectronics, and computing.
• A major challenge is significant volume change in polymer-based conductors during ion doping/de-doping, impacting performance and device longevity.

Purpose of the Study:

• To introduce a novel polymer, poly[3-(6-hydroxy)hexylthiophene] (P3HHT), designed for reduced volumetric changes during ion transport.
• To evaluate P3HHT's potential as a stable organic mixed conductor for advanced electronic applications.

Main Methods:

• Electrochemical absorption spectroscopy to assess ion transport.
• Organic electrochemical transistors to test device performance.
• Thickness change measurements under varying swelling conditions (passive and biased).

Main Results:

• P3HHT exhibited minimal thickness change (+2.5% passive swelling) compared to benchmark polymers like PEDOT:PSS (+90%) and p(g2T-TT) (+10-15%).
• Under bias, P3HHT films showed <10% thickness change, while p(g2T-TT) increased by 75-80%.
• P3HHT films largely retained their original thickness after de-doping, unlike p(g2T-TT).

Conclusions:

• Hydroxylated side-chain functionalization in P3HHT effectively minimizes swelling during ion transport.
• P3HHT presents a promising low-swelling soft mixed conductor for stable and durable bioelectronic and energy storage devices.
• This work expands the design strategies for developing advanced organic electronic materials.