Single, double, and triple layer Prussian Blue, reduced graphene oxide, and polyaniline composite films for electrochromic applications

Nanoporous structures of single, binary, and ternary films from rGO, PANI, and PB materials were prepared to improve the electrochromic (EC) efficiency and electrochemical stability of electrochromic devices (ECD). Structures were prepared by electro-polymerizing aniline monomers onto coated F-doped tin oxide (FTO) glass slides with PB, rGO, or rGO/PB films, while Nickel oxide was formed by electrodeposition. The physical and optical properties of formed films were characterized by XRD, FT-IR, UV-vis, and SEM techniques. The electrochromism of the investigated electrodes was studied in 1 M LiClO4 + propylene carbonate (LiClO4 + PC). The properties of an electrochromic device (ECD) of glass/FTO/rGO @PANI@PB/1 M LiClO4-PC electrolyte/NiO/ FTO/glass were studied. The electrochromic properties of tested thin films were investigated using cyclic voltammograms (CV), chronoamperometry (CA), chronocoulometric (CC), and UV-Vis spectrophotometry studies. The results showed the reversible coloration and bleaching of the ECDs. The hybrid organic-inorganic materialsbased electrodes improved optical modulation, switching speed, and coloration efficiency. For the different fabricated electrodes, corresponding coloring efficiencies were achieved: rGO/PANI/PB (11.3 cm2/C), rGO/PANI (4.5 cm2/C), and PANI/PB (22.8 cm2/C). Also, PANI-based electrode showed lower efficiency than PB (20.4 cm2/ C vs 312 cm2/C). The promising results in this study support the use of rGO/PANI/PB electrode for smart window applications. The fabricated ECD device of (rGO/PANI/PB//NiO) achieved optical modulation (Delta T) of 41 % and switching times of 12.1 s (coloration) and 12.6 s (bleaching) at a wavelength of 625 nm. Regarding durability, the proposed ECD achieved Delta T of 38 % after 3000 cycles, i.e., 92 % of the initial device.