Electrochemical Analysis of <scp>PEDOT</scp> in Acetonitrile Solutions of Ionic Liquids for Active <scp>IR</scp> Technologies

ABSTRACT This study provides the analysis of poly(3,4‐ethylenedioxythiophene) (PEDOT) films via secondary doping for operation in electrochromic devices using ionic liquids, acetonitrile‐based solutions of ionic liquids, and their mixtures for ideal operation electrochemically. For this purpose, PEDOT:Tos films were electrochemically reduced and oxidized with these electrolytes, containing various dopants (TFSI, OTf, BF 4 , PF 6 , and Cl) and their combinations, forming dual‐doped PEDOT films. OTf proved to be an excellent dopant for enhancing the dynamic range (Δ ε = 0.12). Electrochemically oxidized PEDOT:PF 6 /BF 4 resulted in both the highest doping level (30.1%) and conductivity (3500 S/cm) with a dynamic range of Δ ε = 0.10, demonstrating the advantage of incorporating multiple dopant anions. In addition, the use of PF 6 in conjunction with other dopants, such as BF 4 , demonstrated distinct doping behaviors from multiple dopants, as observed from electrochemical analysis. This results present usefulness of PEDOT outside of IR modulation in areas such as ion sensing.