Peng Han

Traditional photonic crystal films are becoming increasingly popular in the fields of smart sensing and optical devices due to their high brightness level, but at the same time there is a lack of color saturation and angle dependence, which seriously affects the application of structural color in visual response and display fields. Here, the optical performance of the photonic crystal films was improved by doping a certain amount of carbon black and carbon quantum dots during the film preparation process. Doping carbon quantum dots can effectively compensate for the optical brightness loss caused by the introduction of black substances by utilizing their self-sustained photoluminescence behavior that matches the photonic bandgap. In addition, the introduction of black nanoparticles can effectively enhance surface-resonant scattering, resulting in low angle-dependent structural colors, further expanding the application of structural color in optical display fields.

Photonic materials with tunable structural colors in response to various stimuli have enabled diverse sensing and displaying applications. However, the changeable colors caused by mechanical deformations may severely confuse the optical readouts for the upcoming wearable photonics. Herein, an extremely stretchable supramolecular organogel is demonstrated with deformation‐insensitive structural colors through an unconventional cascade‐microphase‐separation process among the silica nanoparticles (SiO₂ NPs), silicone oils, and hydrogen‐bonded polymer gel. The resultant sparse and abundant microscale SiO₂ NP aggregates with proper sizes, shapes, and random distributions in the gel matrix serve as rigid structural color domains and secure invariant colors to the whole soft sample under extreme mechanical deformations. Moreover, the dynamic hydrogen bonding of the organogel matrix offers the nanocomposites shear‐thinning and easy‐molding property, making them ideal for color paints in versatile coating applications. The deformable organogel nanocomposites have great potentials in various fields requiring stable colors and open up a new avenue for the development of wearable photonic devices.

The most important properties of noniridescent structural colors of amorphous photonic structures (APS) are sufficient color brightness and saturation, which are difficult to be optimized simultaneously. Herein, highly saturated and brilliant noniridescent structural colors are achieved by introducing graphene nanosheets, which contain a fraction of graphene quantum dots (GQDs), into the short‐range ordered APS. The effective modulation of the photoluminescence (PL) of GQDs by the selective enhancement of absorption at the blue pseudo photonic bandgap edges of the APS boosts the PL with wavelength matching that of the photonic bandgap and thus enables high structural color brightness; the uniform light absorption of graphene nanosheets in the whole visible spectra contributes to the high color saturation. Furthermore, by using APS films with short‐range order as templates, a brilliant colorful humidity sensor is demonstrated. Compared with the conventional sensing platform based on photonic crystals, the humidity sensor with brilliant noniridescent structural colors is more convenient by avoiding the confusing color dependence on the viewing angles. The improvement in the structural color brightness of the APS films by facile graphene doping will facilitate their practical applications in fields of decorations, packaging, pigments, sensors, displays, or other color‐related areas.

Structural colors have profound implications in the fields of pigments, displays and sensors, but none of the current non‐iridescent photonic materials can restore their functions after mechanical damage. Herein, we report the first self‐healable organogel nanocomposites with angle‐independent structural colors. The organogel nanocomposites were prepared through the co‐assembly of oleophilic silica nanoparticles, silicone‐based supramolecular gels, and carbon black. The organogel system enables amorphous aggregation of silica nanoparticles and the angle‐independent structural colors in the nanocomposites. Moreover, the hydrogen bonding in the supramolecular gel provides self‐healing ability to the system, and the structural colored films obtained could heal themselves in tens of seconds to restore storage modulus, structural color, and surface slipperiness from mechanical cuts or shear failure repeatedly.