Scalable and High-Performance Infrared Electrochromic Devices Enabled by Solvent-Engineered PEDOT/PSS Films

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Science

Background:

• Poly(3,4-ethylenedioxythiophene) (PEDOT) based infrared electrochromic devices (IR-ECDs) are promising for dynamic thermal management.
• Current limitations include slow response, poor cycling stability, and challenges in scalable fabrication.

Purpose of the Study:

• To develop a scalable, solution-processed strategy for fabricating large-area, flexible PEDOT/PSS IR-ECDs.
• To improve the performance of PEDOT-based IR-ECDs through enhanced conductivity and charge transport.

Main Methods:

• A one-step solvent post-treatment was employed to selectively remove insulating poly(styrenesulfonate) (PSS) from PEDOT/PSS films.
• Fabrication of large-area, flexible IR-ECDs was achieved using this solution-processed strategy.
• Device performance was characterized through electrochromic switching, cycling stability, and mid-infrared emissivity modulation measurements.

Main Results:

• The solvent post-treatment significantly enhanced film conductivity, accelerating charge transport and enabling robust electrochromic switching.
• The resulting devices exhibited rapid switching behavior and excellent cycling stability.
• A notable mid-infrared emissivity modulation (Δε_{8-14 um}) of 0.23 was achieved.

Conclusions:

• The study provides insights into the infrared electrochromic mechanism of PEDOT/PSS, primarily driven by conductivity changes from ion doping/dedoping.
• When conductivity exceeds ~500 S/cm, long-wave IR reflectance aligns with Drude theory predictions.
• This work opens avenues for scalable, cost-effective, high-performance thermal modulation technologies for applications like adaptive concealment and intelligent thermal regulation.