Liquid, Transparent, and Antideformable Thermochromic Photonic Crystals for Displays

Abstract

According to their characteristics, TPCs can be divided into two types. One type of TPC composites with the ability to change their optical properties only at certain temperatures can be prepared by integrating thermal responsive polymers [40][41][42][43][44] and phase change materials (PCM) [45,46] into PCs, making them suitable candidates for constructing patterns. For example, Ge's group [46] has realized the printing of high-resolution patterns based on the TPC composites with PC-PCM double layers. Another type is TPC gels which can constantly switch their reflection signals at different temperatures through combing PCs with the well-known thermal responsive poly(N-isopropyl acrylamide) (PNIPAM) and their derivatives. [18,[47][48][49][50][51][52][53][54] Asher and co-workers have fabricated outstanding TPC hydrogel [50] by embedding polystyrene colloidal crystals into thermosensitive PNIPAM hydrogel with a low critical solution temperature (32 °C). The lattice distance of the TPC gel decreases as the temperature increases (10-35 °C), leading to the blue shift of the reflection wavelength across the whole visible range. TPCs with switchable peak positions based on the variation of lattice distance also can be realized by PNIPAM inverse opal structures [47,49] or when PNIPAM and their derivative particles are used as building blocks. [18,[51][52][53][54] In contrast, only a few works have proved that the reflectance of TPCs can be tailored at diverse temperatures (15-40 °C) by modulating the

Determining the Local Refractive Index of Single Particles by Optical Imaging Technique

“…This composite nanostructures can be applied in producing optically transparent photonic crystal materials. − The core is a PS nanosphere with an accurate radius of 239.5 nm ( r ) from SEM characterization, and the thickness of the SiO 2 shell ( R – r ) is controlled from 62.5 nm to 201 nm (Figure S5 in the Supporting Information). The theoretical refractive index of core–shell nanospheres ( n core–shell ) can be calculated by , which is plotted as a function of the ratio between core and core–shell volume. The simulated results n PS = 1.547 and n SiO 2 = 1.421 match well with the previous reports. ,,, Accordingly, the measured single-particle refractive index of core–shell nanostructures is well-fitted with the above equation by varying the ratio of the core radius and shell thickness, as shown in Figure B.…”

“…The theoretical refractive index of core–shell nanospheres ( n core–shell ) can be calculated by , which is plotted as a function of the ratio between core and core–shell volume. The simulated results n PS = 1.547 and n SiO 2 = 1.421 match well with the previous reports. ,,, Accordingly, the measured single-particle refractive index of core–shell nanostructures is well-fitted with the above equation by varying the ratio of the core radius and shell thickness, as shown in Figure B. This strategy can also be utilized to differentiate various components of single particles down to micronano scale.…”

“…38−40 The core is a PS nanosphere with an accurate radius of 239.5 nm (r) from SEM characterization, and the thickness of the SiO 2 shell (R − r) is controlled from 62.5 nm to 201 nm (Figure S5 in the Supporting Information). The theoretical refractive index of core−shell nanospheres (n core−shell ) can be calculated by 41,42 i k j j j j j y…”

Artificial Chameleon Skins Active Mimicking Reversible Off/On Structural Colors of Insect Wings

“…[3] Under the excited state, panther chameleons can actively alter the distance of neighboring guanine particles and thus their structural colors by contracting or stretching iridophore cells. Inspired by these, artificial chameleon skins [6][7][8][9][10][11][12][13][14][15][16] have been extensively investigated to mimic the characteristics of the dynamic change of colors, which are potentially useful for optical devices, [17][18][19] displays, [20][21][22][23][24][25][26] sensing, [7,18,19,[27][28][29][30][31][32][33][34] printing, [11,[35][36][37][38][39] and anticounterfeiting. [8,[40][41][42][43][44][45][46][47]…”

Transparent Encryption of Nanostructured Photonic Patterns by Erasing the Structural Colors of Visible Patterns: Implications for Anti-Counterfeiting and Information Encryption Applications

“…Compared with conventional chemical dyes and pigments, the structural colors of PCs have many advantages of never fading, anti-photobleaching, and environmentally friendly properties . These unique characteristics endow PCs with prospects of prosperity for various applications in the fields of anti-counterfeiting, − printing, − displays, − physical and chemical sensing, − information encryption, − pigments, − photocatalysis enhancements, and solar cells …”