Enhanced Coloration Efficiency of Electrochromic Thin Film Based on TiO2 and Chitosan

Abstract

Self-assembled multilayer films containing TiO 2 and chitosan (CS) were prepared using layer-by-layer method (LbL). The composite film fabricated on quartz and fluorine-doped tin oxide substrates was investigated using UV-vis spectroscopy, scanning electron microscopy (SEM), cyclic voltammetry (CV) and in situ chronoamperometric (CA) electrochemical measurements. The results of the UV-vis spectra confirm the uniformity of each deposition cycles. The electrochemical behavior of TiO 2 has the typical property of a surface-confined electrochemical process. The composite film displays high electrochromic performance, with the coloration efficiency 33.3 cm 2 /C of and optical contrast of 17.1% at 800 nm. Furthermore, the film achieved a fast switching speed of 6.0 s and 0.5 s for coloration and bleaching, respectively. The composite material undergoes transitions from colorless to dark blue when the potential is switched from +2 V to-2 V. The electrochromic performance of the LbL film containing TiO 2 and CS indicates that this material is highly beneficial in view of an application in electrochromic devices.