Multicolor Electrochromic Display and Patterned Device Based on Hollow-SiO₂-Supported WO₃ Photonic Crystals

Abstract

Electrochromic photonic crystals (PCs) have been intensively studied in the field of display, sensors, and intelligent materials due to their tunable brilliant structural colors. The mostly studied electrochromic PCs are based on the tunable lattice parameter after electrifying; namely, the electrochromic process is caused by the structural change of PCs. Besides the lattice parameter, the refractive index is another key factor to determine the structural color of PCs. Here, a kind of hollow-SiO 2 -supported WO 3 (H-SiO 2 /WO 3 ) PCs is designed, where the refractive index of the WO 3 portion is changeable under charging. Benefiting from the support effect and tunable thickness of H-SiO 2 , large-area PC samples with good surface morphology and bright multicolor output are prepared. The reflection peaks of these composite PCs can shift by 30−90 nm, and their corresponding colors changed obviously after the voltage was applied. After being pixelated by laser-marking, the H-SiO 2 /WO 3 PCs can dynamically display different numeric and alphabetic patterns in an electric-driven writing and erasing process. Not only does this composite PC structure broaden the color change range of WO 3 -based materials but also avoids the structural change in the electrochromic process. This work provides more possibilities for electrochromic PCs in the field of color-changing pattern displays.

Recent progress in low‐swellable polymer‐based smart photonic crystal sensors

“…Inverse opal SPCSs can also be composed of inorganic materials, especially metal oxide materials with high refractive index, such as titanium dioxide (TiO 2 ), [260] tin dioxide (SnO 2 ), [261] and tungsten trioxide (WO 3 ). [21] A high refractive index can usually improve the reflection intensity of PC and enhance the structural color. On the one hand, the filled polymer enhances the stability of the inverse opals, on the other hand, it can give some specific stimulus responses to the system.…”

“…Inverse opal polymers are essentially porous materials, and the connected macropores are particularly suitable for the design and construction of micro-reactors due to the outstanding mass transfer. [21,192,262,263] The properties of inverse opal-derived SPCSs mainly depend on the chemical and physical properties of the polymer skeleton. They are generally films with good mechanical properties.…”

“…[16] PCs, as smart materials with built-in structural color sensing, have been attracting much attention. [17][18][19][20][21] Most current stimulus-responsive PCs are structured polymers fabricated by template replication or negative replication, especially Low-swelling polymers (LSPs). [22,23] Based on the limited visible range, usually a small degree of swelling can cause the diffraction displacement of PC to cover the entire visible region.…”

Three‐Dimensional Ordered Macroporous Amorphous WO3 Arrays for Zinc‐Based Electrochromic Device with Large Light Modulation and Fast Switching

“…Electrochromic smart windows with excellent light modulation capabilities are widely used in the fields of building energy conservation, next‐generation displaying, and security encryption. [ 1–4 ] WO 3 ‐based materials with features in diverse phases and multivalent states, excellent electrochromic performance, environmental friendliness, and low cost, are promising candidates for electrochromic devices. [ 5–7 ] The WO 3 based electrochromic devices perform coloring and bleaching mainly involving in redox reactions with electrolyte solute ions.…”

Electrically Responsive Photonic Crystals with Enhanced Suspension Stability and Color Saturation for Electrophoretic Displays and Smart Windows

“…For example, liquid crystals (LCs) can be infiltrated into the void of PCs, and then dynamic color is obtained by changing the refractive index of PCs under an electrical field. − However, the driving voltage usually reaches as high as hundreds or thousands of volts, whereas the wavelength shifts only tens of nanometers. Besides, electrochromic materials, such as WO 3 and ethyl viologen, , can also be introduced into PCs to adjust their refractive index under an electric field. The challenge facing this kind of ERPCs is still the limited tuning range of structural colors.…”