Fig. 1. (a) Scheme of a dynamic color display using stepwise FP cavity array based on Sb₂S₃ switched between amorphous (left column) and crystalline (right column) states. The stepwise FP cavity array consists of air/ Sb₂S₃/Au with different heights of the Sb₂S₃ strips. The reflected colors of the structure are associated with the phase and thickness of the Sb₂S₃. Inset: Schematic of the stepwise FP cavities array. Pixelated Sb₂S₃ strips of different heights generated by lithography-free fs laser patterning are sandwiched between an air-capping layer and an Au mirror reflector. Resonant modes can be created in the FP cavity, selectively reflecting light with particular colors. (b) Atomic structures: Sb₂S₃ with the different phases of amorphous and crystalline are shown on enthalpy-order schematic plot. The photo images of the stepwise FP resonators array (c) before crystallizing, (d) after crystallizing the Sb₂S₃ strips in the cavity. (e) The reversibly switchable photo images of the strip (ii) in figure (c). Scale bar 100 μm.

Fig. 2. (a) Scheme of the reversible phase change of the Sb₂S₃ film with the various heights integrated with an Au reflector: AD-AM Sb₂S₃ is first annealed above 543 K to change to CR Sb₂S₃ using a hot plate. The fs laser pulses (35 mW) are triggered to heat the CR Sb₂S₃ film above 801 K that re-amorphizes the CR Sb₂S₃. Subsequent quenching results in the MQ-AM Sb₂S₃. To recrystallise the MQ-AM Sb₂S₃, for which a temperature above 543 K but below 801 K is required, the fs laser pulses with lower power (25 mW) are employed. (b) Visible–NIR complex refractive index of 50-nm-thick Sb₂S₃ laminate at the structural states of the AD-AM (red line), CR (blue line), MQ-AM (orange line), and R-CR (green line), where the refractive index is measured using an ellipsometer over a spectral range of 400 to 900 nm.

Fig. 3. (a) The measured reflectance spectra (left column) and colors (right column) of the four representative tiles (i–iv) highlighted in Fig. 1(c) during the phase transition of Sb₂S₃. (b) Color palettes of the structures in amorphous (left column) and crystalline (right column) states as varying the thickness of Sb₂S₃ from 5 to 30 nm. (c) Raman spectra of the color patch in Fig. 1(c) (ii) for both amorphous and crystalline states, respectively. (d) Color coordinates from the experimentally measured spectra plotted on the CIE 1931 chromaticity figure of the devices as varying the T_SbS from 5 to 30 nm.

Fig. 4. The simulated (a) reflectance spectra and (b) color palettes of the devices in structural states of amorphous and crystalline for the different thicknesses of Sb₂S₃ of T_SbS = 10, 15, 20, and 30 nm, corresponding to the color tiles (i−iv) shown in Fig. 1(c).

Fig. 5. (a) The SEM picture of the fabricated “Bing Dwen Dwen” display (left column) and optical micrographs of the “Bing Dwen Dwen” (middle column) before crystallizing, (right) after crystallizing the Sb₂S₃ in the device. (b) The SEM picture of the fabricated “DUT” display (left column) and optical micrographs of the “DUT” (middle column) before crystallizing, (right) after crystallizing the Sb₂S₃ in the device. Scale bar 200 μm.