Solvent Annealing Influence of PEDOT on Its Electrochemical and Electrochromic Properties

The study of effect of solvent annealing on the optoelectronic properties of polymers is not new research hotspot, but the influence of solvent annealing on the electrochemical and electrochromic properties of PEDOT remains unexplored. This paper investigates the effects of three different solvents-chlorobenzene (CB), tetrahydrofuran (THF), and dimethylformamide (DMF)-on the self-assembly of PEDOT films and compares their thermal, morphological, electrochemical, and electrochromic properties. PEDOT annealed with DMF exhibits a highly crystalline film morphology, which increases the difficulty of ionic doping/undoping and leads to suboptimal electrochemical and electrochromic stability. After CB annealing, PEDOT forms a relatively gentle melting peak. In addition to a certain degree of crystallinity, the polymer film also exhibits cracking, which severely impairs the electrochromic performance. After THF annealing, PEDOT exhibits a gentler melting peak, a surface morphology that is more favorable for electrochemical and electrochromic performance, ultimately achieving an optical contrast of 28%, the fastest response time of 1.1 s, and the highest coloration efficiency of 184 cm² C^-1. The impact of solvent annealing on PEDOT's electrochromism is significantly different, which will guide the electrochemical and electrochromic properties of PEDOT analogs and derivatives under the influence of different solvents.