Structural color via layer-by-layer deposition: layered nanoparticle arrays with near-UV and visible reflectivity bands

Highly Efficient Trans-Reflective Color Filters Incorporating TiO2-MgF2Multilayer Stacks

“…Under the limited availability of low-index materials, multilayered structural colors were actively developed by drawing upon porous or columnar SiO2 or TiO2 as a low-index layer, focusing mainly on the reflection mode while ignoring the transmission color response [7][8][9][10][11]. However, this method suffered from a couple of drawbacks that mostly stem from the porous and/or columnar microstructure of the films.…”

“…However, the application of the material combination towards the realization of structural color filters has rarely been discussed. It should also be remarked that the previous reports on multilayered structural colors mostly dealt with their operation in the reflection mode while ignoring the color filtering in transmission-mode [7][8][9][10][11][12][13]. A transmission-type color filter is of paramount importance in view of its potential applications in transmissive displays and sensors and thus the investigation of color filtering of such multilayer stacks in both reflection and transmission modes would be highly desirable.…”

“…The angular dependence of the transmission/reflection spectra was also meticulously monitored with respect to light polarization. The proposed structural colors, tapping into multilayer stacks incorporating dense multilayers of TiO2 and MgF2, are anticipated to lead to more stable color response compared to porous and columnar counterparts, which are either anisotropic or are potentially vulnerable to the environment, considering that gases or fluids diffusing or penetrating into the device might change the optical properties of the material undesirably [7][8][9][10][11]14]. The appeal of the work is not only the scope of the material composition that has been utilized for structural color filter applications but also the realization of transreflective color filters, featuring an optimal stop band assuming an appropriate bandwidth within the visible regime, which has not been rigorously examined yet.…”

“…Recently, multilayer stacks composed of periodical layers of high (H) and low (L) index layers, particularly received extensive attention as a vehicle to realize structural color filters. Such multilayered structural colors incorporating dense or nano-porous TiO2 and SiO2 were actively studied thanks to their excellent properties, such as high transparency, non-toxicity, chemical stability, good film adhesion, and mechanical durability [7][8][9][10][11][12][13].…”

Bio-inspired iridescent layer-by-layer assembled cellulose nanocrystal Bragg stacks

“…Constructive interference of reflected light, or Bragg reflection, can be achieved by such systems when the optical thickness of each periodic layer is on the order of λ/4 and the viewing angle is close to 90°. 6,7 Successful, affordable fabrication of such structures could make Bragg reflectors useful for sensing, 8,9 optical filters, 10,11 and the widespread replacement of pigment-based coatings. 12,13 The iridescent effect can only be generated by structural systems and is particularly conspicuous to the human eye, which is appealing to industries where aesthetics are important.…”