Infrared Electrochromic Properties Regulation of Poly(thieno[3,2- <i>b</i> ]thiophene) Porous Films Prepared by Electrodeposition

Fused thiophene-based conjugated materials have received significant attention due to their rigidity and planar structure, which enhance the performance of electronic devices. In this study, poly(thieno[3,2-b]thiophene) (PTT) films were prepared via electrodeposition for use as electrochromic materials. The effects of electrodeposition time and monomer concentration on the surface morphology and infrared electrochromic properties of the films were systematically investigated. The obtained polymer PTT was characterized by using cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. The film exhibits a color change from red in the reduced state to blue-green in the oxidized state. The properties of PTT, including its electrochemical behavior, response time, stability, and emissivity, were explored. The average emissivity change (Δε) of the PTT film in the wavelength ranges of 3–5 μm and 8–14 μm reached 0.23. The coloring and bleaching times were 3.5 and 1.5 s, respectively, and the cycling stability was 84.3% after 4000 s. This study demonstrates the feasibility of applying thieno[3,2-b]thiophene materials in the field of infrared electrochromism.