Study of Two Inorganic Particles in PMMA Electrochromic Devices Based on the Difference of Work Function

Abstract

In electrochromic devices, the electrolyte layer is not only an electrode conduction medium but also provides compensation ions for electrochromics. Here, three kinds of composite electrolytes, PMMA/SiO2, PMMA/TiO2, and PMMA/SiO2/TiO2, were prepared and assembled with poly(methyl methacrylate) (PMMA) as polymer matrix and doped with inorganic particles of silicon dioxide (SiO2) and titanium dioxide (TiO2), to study the effect of doping two kinds of inorganic electrolyte particles on the performance of electrochromic devices. The optical contrast and cycling stability of the electrochromic devices assembled with PMMA/SiO2/TiO2 composite electrolytes were significantly improved compared with devices composed of the other three electrolytes. Cyclic voltammetry analysis showed that the lithium ion diffusion coefficient of the electrochromic device with PMMA/SiO2/TiO2 composite electrolyte composite electrolyte was the largest at 2.5×10-14 cm2/s. Enhancement of the electrochromic performance is mainly due to the fact that the work function difference between SiO2 and TiO2 in the figure of merit will lead to the directional movement of charge, accelerating the Li+ transport rate and further optimizing the electrochemical performance of the composite electrolyte. This study provides an effective method to improve the performance of electrochromic devices.