PROPERTIES AND PROSPECTS OF USAGE OF ELECTROCHROMIC MATERIALS

The review considers phenomenon of electrochromism, presents the main characteristics of electrochromic materials, such as spectral efficiency and switching speed. The features of their preparation influence of synthesis methods and impurities on electrochromic characteristics are shown. From a large number of electrochromic materials, oxides of some transition metals are considered, in which changes in redox states between p– and d– sublevels are observed. These are oxides W, Ni, Nb, V, each of which has its own special electrochromic properties. For example, due to the rapid intercalation under the action of an electric field of protons and lithium ions, tungsten trioxide is considered the most promising material, which is already used in smart glasses and hydrogen sensors. Materials based on nickel oxide have an anodic electrochromic effect, which can be used in conjunction with cathodic electrochromic materials similar in color, such as niobium and vanadium oxides. Niobium oxide is interesting as mechanically stable films with wide spectral characteristics, the main efficiency of electrochromic coloring of which falls on the visible region. For oxide compounds based on vanadium, a combination of thermochromic and electrochromic properties was observed, which makes it possible to control their absorption depending on the temperature. This property is interesting for creation of thermo–optic camouflage devices for military and civilian use. Among organic electrochromic materials, materials based on polythiophene, polyaniline and phthalocyanine complexes of copper and nickel have been isolated. These materials have multichromic properties depending on applied potential and have high efficiency of electrochromic effect due to narrow spectral absorption region.