The Electrochromic Properties Of Tungsten Oxide And Nickel Oxide Films

Electrochromic devices are composed of electrochromic materials as core,substrate,transparent conductive layer,cathodic electrochromic films,electrolyte and anodic electrochromic films,which played an important role in building energy saving by controlling the transmittance of electrochromic films.However,the current electrochromic devices not only have low optical modulation amplitude,but also restrict the devices of the selective regulation including the optical(visible region)and heat(near infrared region),because the electrochromic films do not have the ability to adjust the visible and near infrared transmittance selectively and independently.Therefore,in this paper,WO3/ITO multilayer films as cathodic electrochromic layer,SnO2-Sn-doped NiOx composite films as anodic electrochromic layer,and complementary solid-state electrochromic devices are studied as research objects.To solve the problems which WO3 films do not have dynamic-controlled ability and NiOx films do not have large optical modulation range,the following three main research works were carried out.(1)The preparation methods and electrochromic properties of WO3/ITO multilayer films were discussed.The results showed that WO3/ITO multilayer films could block near-infrared and visible light selectively and independently and enhance the spectral modulation of the WO3 films ability after depositing a layer of ITO nanocrystalline films between the WO3 films and the transparent conductive layer.(2)It was found that the contents of Sn and the thickness of ITO films played important roles in WO3/ITO multilayer films for tunable near-infrared and visible-light transmittance.In the research conditions,When the Sn content was 12.5%and the thickness of ITO films was 230±20 nm,the WO3/ITO multilayer film have best electrochromic properties,which the visible coloring and fading contrast was 38%,with the near infrared coloring and fading contrast as 13.06%.(3)The effect of the heat treatment temperature on electrochromic properties of NiOx films was studied.The results showed that the NiOx film mainly controlled in the visible light transmittance.In the research conditions,when the heat treatment temperature was 450 ℃,the optical modulation amplitude of NiO films were the largest,with the visible coloring and fading contrast as 22.67%.(4)the effect of the different Sn:Ni molar ratio on microstructure and electrochromic properties of NiOx films was studied.The results showed that the Sn element was got into NiOx lattice in the form of Sn4+with a small content of Sn:Ni molar ratio,which effectively inhibited the formation of Ni3+and improved the transmittance of the NiOx films in bleached state,thus increased the contrast degree of the decolorizing films.With the increase of Sn:Ni molar ratio,the superfolus Sn4+ combined with O2-to form SnO2 nanocrystalline,which further improved the visible coloring and fading contrast.But when the content of the Sn elements was too high,the Ni ion composition decreased and the color fading contrast of the film decreased.In the research conditions,when the molar ratio of Sn:Ni was 0.3:1,the electrochromic properties of the SnO2-Sn-doped NiOx composite films films were the best,and the visible coloring and fading contrast was 41.96%.(5)WO3/ITO multilayer films as.cathodic electrochromic films and the SnO2-Sn-doped NiOx composite films as anodic electrochromic films and PMMA based electrolyte were composed to complementary all-solid-state electrochromic devices.the effects of PMMA based electrolyte with different mass fraction on the properties of electrochromic devices were studied.In the research conditions,when the mass fraction of PMMA was 12.5%,the electrochromic performance of the device was the best,which the visible coloring and fading contrast was 48.29%,with the near infrared coloring and fading contrast as 10.30%.