Investigating the effect of electrolyte types with various ionic liquids on the electrochromic performance of PEDOT:PSS based LbL multilayers

The objective of the study is to investigate the electrochromic performances of layer-by-layer (LbL) multilayered thin film electrode prepared from linear polyethylene imine (LPEI) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) on PET-ITO substrate in the presence of different types of electrolytes. For this purpose, the electrochromic behaviors of (LPEI/PEDOT:PSS)₁₀ is performed in LiClO₄/propylene carbonate (PC) and two different ionic liquids (IL) namely N-methylimidazolium tetrafluoroborate (Melm-BF₄) and 2-hydroxy ethyl ammonium formate (2-HEAF), as a function of IL content and scanning rate. The optical contrast value of (LPEI/PEDOT:PSS)₁₀ film is determined as 58.4% in the existence of 10 wt% of 2-HEAF as the electrolyte. The coloration efficiency of this film is determined as 606.7 cm²/C, which this value was greater approximately four times than 1 M LiClO₄/PC. According to the obtained results, 2-HEAF has been evaluated as a suitable electrolyte alternative for (LPEI/PEDOT:PSS)₁₀ film due to its better optical contrast and coloration efficiency compared to other electrolytes.