Electrochromic Poly(DNTD)/WO₃ Nanocomposite Films via Electorpolymerization

Abstract

Poly(DNTD,N,N′-di[p-phenylamino(phenyl)]-1,4,5,8-naphthalene tetracarboxylic diimide) and its nanocomposite film incorporated with WO3 nanoparticles was prepared by a facile electropolymerization method on an indium in oxide (ITO) coated glass slide from the DNTD monomer and WO3 nanoparticles suspended methylene chloride solution. The morphology and microstructure of the nanocomposite film were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The SEM image shows that the WO3 nanoparticles are uniformly embedded in the polymeric matrix. The nanocomposite film also displays smooth topography with evenly sized and uniformly distributed nanoparticles under high resolution AFM observations. An air-stable electrochromical window was assembled and obtained by a homemade electrochemical cell to study the electrochromism and stability of the nanocomposite film. The composite film exhibits multiple colors at both the cathodic and anodic potentials, i.e., light blue at −1.4 V, orange red at −0.8 V, colorless at 0 V, orange green at 0.8 V, light blue at 1.0 V, and deep blue at 1.2 or 1.4 V vs Ag/AgCl in propylene carbonate containing 1.0 M LiClO4 electrolyte. The UV–visible incorporated electrochemical spectroscopy coupled with amperometry were also employed to study the composite film under different potentials in the range of −1.4 to 1.4 V vs Ag/AgCl. The composite film also shows stable electrochromism even after 100 scans. The thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) analysis suggest the hydrogen bonding formed between the monomers and WO3 particles, resulting in an increased initial oxidation potential for the monomer during the poly(DNTD)/WO3 nanocomposite film formation.