Photochromic materials are widely investigated due to their vivid color transformation for many real applications. In this work, a new kind of multiangle photochromic photonic crystal (PC) material with high robustness and long durability for smart phone decoration and anticounterfeiting features is fabricated. After thermal mixing of spiropyran powder and monodisperse core-interlayer-shell (CIS) particles, a large-area and high-quality photochromic PC film has been prepared by the selfdesigned bending-induced ordering technique (BIOT). The spiropyran powder can be well dispersed in the order-structured PC system, so the perfect synergistic combination of photochromism and angle-dependent structure colors can be achieved. The color-switching test for the as-prepared photochromic PC film proved its excellent reversibility and stability. Because of the excellent flexibility of the photo-cross-linked PC films, they can be designed and cut into various shapes with high robustness and long durability. Interestingly, a temperature-controlled photochromic effect was found in this photochromic PC system. Therefore, the as-prepared photochromic PC films can play a significant role in the fields of smart decoration and anticounterfeiting by their unique color switching effects under different stimuli. More importantly, our work verified the feasibility of this route to prepare a series of large-sized advanced smart PC devices by adding versatile functional materials.
Reflective display devices, especially for electrochromic
photonic
crystals (ECPCs), are of great interest to researchers due to their
convenient control approach, wide color regulation range, fast response,
and low power consumption. Herein, liquid colloidal crystals (LCCs)
of SiO2 nanospheres were prepared through an evaporation-induced
self-assembly method and used as a reflective unit for fabricating
dynamic ECPC devices. The ECPC device exhibited brilliant controllable
structural color across the visible spectrum under low voltages (<3.5
V). Based on the in situ ultra-small-angle X-ray scattering results
and reflective spectra, regulatory rules of the dynamic ECPC device
concerning a color tunable range, reflectance intensity, response
speed, and cyclic performance were set up, and the relationship between
slurry concentration, electrode spacing, and viewing angle was established.
Furthermore, a dynamic mechanism was revealed for explaining the responsive
behaviors of reflection spectra during the electrical modulation,
which is significant for the development of ECPC devices in the future.
Based on the parameter optimization and structure design of the dynamic
ECPC device, a pressure-responsive electrochromic prototype device
was constructed with rapid response, dynamic structural color, and
good reversibility, which demonstrated its great potential in reflective
display units and multifunctional sensors.
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