1. Microstructural characterization of ITO/GdO_xH_y bilayer film(a) XRD patterns of ITO/GdO_xH_y before (blue) and after (red) illumination; (b) Schematic crystal structure of GdO_xH_y; (c-f) SEM images of cross section (c, e) and surface (d, f) of thin film samples with the insets in (d, f) showing the corresponding AFM images

2. XPS spectra of ITO/GdO_xH_y before and after the illumination(a) C1s; (b) O1s; (c) Gd4d

3. Effect of sputtering atmosphere on film properties(a) XRD patterns of films prepared under different sputtering atmospheres; (b) Value at the point of maximum change in transmittance for films grown under different sputtering atmospheres; (c) Bleaching time of films under different sputtering atmospheres; (d, e) Transmittance spectra of films before and after stability test

4. Effect of temperature on the bleaching rate(a) Energy-barrier relationship between the "bleached state (1)" and "coloring state (2)" at room temperature; (b) Energy-barrier relationship between "bleached state (1)" and "coloring state (2)" when heated; (c) Bleaching rates of films at different temperatures; (d) Variation of transmission spectra of films with time and placed in a temperature field of 70 ℃; (e) Relationship between optical contrast, band gap (Tauc-plot method), and annealing temperature; (f) Transmittance spectra of GdO_xH_y films at different annealing temperatures; Colorful figures are available on website

5. Transimittance and emissivity spectra of the ITO/GdO_xH_y bilayer film before and after light illumination

6. Demonstration of film versatility(a) Variation of emission temperature of ITO (left), ITO/GdO_xH_y (middle), and glass (right) under UV irradiation; (b) Optical lithography of the “SICCAS” pattern on the surface of the sample by UV light projection