Study on Raman spectra of electrochromic c-WO3 films and their infrared emittance modulation characteristics

Polycrystalline tungsten oxide films with good electrochemical stability were prepared by dc reactive sputtering method. The Raman spectra of these films show that the W6+ ions were reduced to W5+ with the co-intercalation of Li+ ions and electrons. Intercalated electrons entered extended states of crystalline tungsten oxide and caused infrared reflectance variation, therefore, the emissivity of WO3/ITO/glass can be reversible modulated between 0.261 and 0.589.