Fig. 1. Optical constants of GSST and GST: (a) amorphous state; (b) crystalline state. (c) Multi-layered structure proposed in this paper, sub/Ag/LaTiO₃/GSST/LaTiO₃/air, and the way it modulates the incident light to dynamically reflect different colors.

Fig. 2. Multi-layered structure: sub/Ag/LaTiO₃/GSST/LaTiO₃/air. (a)–(c) The admittance trajectory diagram of the red, green, and blue multi-layered structure without the AR unit. (d)–(f) The admittance trajectory diagram of the red, green, and blue multi-layered structure with the AR unit.

Fig. 3. (a) Thickness effect of the GSST layer on the spectra of the structure mentioned above: the x-axis is the wavelength, the y-axis is the GSST thickness, and the z-axis is the reflectance; the color blocks between are equipped with GSST thicknesses of 5, 10, 20, 30, and 55 nm from bottom to top. (b) Thickness effect of LaTiO₃ dielectric layers on the colors of the structure mentioned above. (c) Comparison of the color gamut of the same structure mentioned above but with different phase change materials: GSST or GST.

Fig. 4. Properties of single-layer GSST films. (a) Spectra of samples with a thickness of 10 nm at different heating temperatures. (b) Spectra of samples with a thickness of 50 nm heated at 350°C for different heating time; (c) XRD patterns of films annealed at different temperatures. (d) Pictures of single-layer GSST films taken before and after phase transition.

Fig. 5. Optical spectra for five colors and their chromaticity coordinates: (a) chromaticity coordinates: solid for “a” representing amorphous and hollow for “c” representing crystalline; (b) red; (c) green; (d) blue; (e) yellow; and (f) purple (red for as-deposited, blue for annealed, and green for design).

Fig. 6. Experimental results. (a) SEM images (top left); freshly prepared physical samples (bottom left); control graphs of samples before and after annealing (right). (b) Film layer rupture (inset is the image after 10 times magnification under a microscope). (c) Process optimization of thermal annealing time.