The investigation of surface roughness of substrate on electrochromic characteristics for PMeT thin film

The objective of this study is to investigate the influence of surface roughness on electrochromic characteristics. The rough surface of indium tin oxide/glass (ITO/Glass) was prepared by wet etching. And the poly (3-methylthiophene) (PMeT) has been deposited on ITO/Glass by potentiostatic method. The electrochromic behaviors of the PMeT/ITO/Glass were performed in 0.1 M lithium perchlorate (LiClO₄)/propylene carbonate (PC) electrolyte. Compared with the oxalic acid ((COOH)₂·H₂O) and ferric chloride + hydrochloric acid (FeCl₃+HCl) solutions, the ITO/Glass has high surface roughness when the ITO/Glass was etched in (COOH)₂·H₂O solution. The PMeT/ITO/Glass has the best transmittance variation (ΔT(%)) (25 %) at 450 nm after the ITO/Glass was etched in (COOH)₂·H₂O solution for 160 sec. And, the PMeT/ITO/Glass has the best transmittance variation (ΔT(%)) (5 %) at 650 nm after the ITO/Glass was etched in FeCl₃+HCl solution for 60 sec. Furthermore, the experimental results observed that the color of PMeT/ITO/Glass was changed from blue (oxidation state) to red (reduction state).