Enhancing infrared electrochromic properties of the poly(styrene sulfonate) doped polyaniline composite film by morphology regulation

Infrared electrochromic device based on polyaniline (PANI) possesses the ability to regulate infrared radiation, which has a great application prospect in the field of satellite intelligent thermal control. However, it is still challenging to efficiently fabricate uniform and dense PANI functional layer with excellent infrared electrochromic properties. Here, we demonstrate the use of polymer additive to promote deposition of PANI with smooth and dense morphology by inducing uniform electrochemical deposition rate on the electrode surface and inhibiting the growth of PANI in three-dimensional direction through adsorption mechanism. By adding a low concentration of poly(styrene sulfonate) (PSS) to the electrodeposition solution, the PANI film with uniform and compact micromorphology was prepared with excellent infrared electrochromic property, which can realize the modulation of emittance more than 0.4 and 0.45 in the range of 8 ∼ 14 μm and 2.5 ∼ 25 μm, respectively. Furthermore, the infrared electrochromic device that employ the optimized PANI functional film and adsorbing ionic liquid porous gel electrolyte was constructed. Through high and low temperature cycle test (1000 cycles) and vacuum environment test, the device exhibits wonderful durability and can achieve large emissivity modulation in the wavelength range of 2.5 μm ∼ 25 μm (Δε = 0.38). Meanwhile, the transient thermal analysis of the heat dissipating plate attached with the infrared electrochromic device exhibits that the device has an excellent potential for the purposes of efficient thermal management of the satellite.