Sharp scattering spectra induced brilliant and directional structural colors

Abstract

Structural color materials, which generate colors through the interaction between light and nano-microstructures, have always been research hotspots in the fields of display, anticounterfeiting and stimuli-responsive materials. Structural colors based on scattering have received increasing attention due to their wider viewing angles than that originating from the specular reflection of photonic crystals. However, the wide scattering spectrum of an amorphous structure leads to lower purity and brightness of the appeared colors. Few researchers have focused on the scattering of ordered structures due to their strong reflection and diffraction in the visible regions. In this work, by building ordered films (OFs) using SiO 2 spheres (refractive index n = 1.46) with a diameter of 300-500 nm, for the first time, sharp scattering spectra with narrow full width at half-maximum (FWHM, 24 nm) were generated. Importantly, under ambient light, brilliant colors covering the entire visible region can be observed, and a formula was proposed to calculate the scattering spectra of OFs. Moreover, rainbow structural color was realized under irradiation of the nonparallel light, and fullspectrum structural color patterns were fabricated using building blocks with a single particle size by a spraying method. Finally, a composite structure was constructed to explore possibilities in the field of flexible transparent displays.

Simultaneous enhancement of fluorescence intensity, thermometric sensitivity and SNR of upconversion thermometers via optical field localization

“…The formation mechanism of structural color can be attributed to the scattering effect of light by the ordered PS sphere array. 41 This experimental result was also verified by the FDTD numerical simulation, which was in good agreement with the experimental observation (Fig. S16, ESI †).…”

Upconversion Nanoparticle-Integrated Bilayer Inverse Opal Photonic Crystal Film for the Triple Anticounterfeiting

“…The M-UCNPs were deposited on the surface of the optimized bilayer IOPC with double PSBs, which was matched well with the green emission (540 nm, 540-layer) and the excitation wavelength (808 nm, 808-layer) of M-UCNPs simultaneously to enhance the luminescence. Generally, the structural colors of the PC were observed in specular angles; however, according to our previous work, sharp scattering spectra induced brilliant and directional structural colors that appeared in nonspecular angles when the PSB was located in the NIR region . As illustrated in Scheme , (I) on the front of the film (540-layer), reflection structural colors from green to blue under the specular angles were observed.…”

“…On the backside, as shown in Figure c, by fixing the angle between the incident light and the detector at 35° (α 1 ), the scattering spectrum was detected by changing the angles between the sample and the detector from 10 to 35° (α 2 ). According to the Mie theory, sharp scattering-induced bright structural colors can be observed when the ordered structure whose PSB is located in the NIR regions . The detailed angle-dependent scattering spectra are recorded in Figure d.…”

“…Generally, the structural colors of the PC were observed in specular angles; however, according to our previous work, sharp scattering spectra induced brilliant and directional structural colors that appeared in nonspecular angles when the PSB was located in the NIR region. 48 As illustrated in Scheme 1, (I) on the front of the film (540-layer), reflection structural colors from green to blue under the specular angles were observed. (II) Scattering colors showed the different color ranges from red to blue on the back (808-layer) of the film at nonspecular view angles in natural light.…”

Low-Angle-Dependent Anticounterfeiting Label Decoded by Alcohol Tissue Wiping Based on a Multilayer Photonic Crystal Structure

“…Initially, the special iridescent structural colors of the monolayer PC structures were employed in the optical anticounterfeiting field. − With the emphasis on information security, the requirement of the anticounterfeiting label has changed from visible for the naked eye to revealable under a special stimulus. Thus, the responsive material was introduced into the monolayer PC structure .…”