Wear-resistant surface coloring by ultrathin optical coatings

Abstract

We design, fabricate, optically and mechanically characterize wearable ultrathin coatings on various substrates, including sapphire, glass and silicon wafer. Extremely hard ceramic materials titanium nitride (TiN), aluminium nitride (AlN), and titanium aluminium nitride (TiAlN) are employed as reflective, isolated and absorptive coating layer, respectively. Two types of coatings have been demonstrated. First, we deposit TiAlN after TiN on various substrates (TiAlN-TiN, total thicknesses <100 nm), achieving vivid and viewing-angle independent surface colors. The colors can be tuned by varying the thickness of TiAlN layer. The wear resistance of the colorful ultrathin optical coatings is verified by scratch tests. The Mohs hardness of commonly used surface coloring made of Si-/Ge-metals on substrates is <2.5, as soft as fingernail. However, the Mohs hardness of our TiAlN-TiN on substrates is evaulated to be 7-9, harder than quartz. Second, Fano-resonant optical coating (FROC), which can transmit and reflect the same color as a beam split filter is also obtained by successively coating TiAlN-TiN-AlN-TiN (four-layer film with a total thickness of 130 nm) on transparent substrates. The FROC coating is as hard as glass. Such wearable and color-tunable thin-film structural colors and filters may be attractive for many practical applications such as sunglasses.

3D Imprinting of Voxel‐Level Structural Colors in Lithium Niobate Crystal

“…As a recording technique, robust multichannel information recognition is a highly valuable capability and represents the developmental trend of structural colors. [ 27 ] The 3D writability of MA coloration and the transparency of LiNbO 3 crystal confer at least four readout modes on MA colors (Figure S14A, Supporting Information), including front and back readout using transmission and reflection illumination respectively. Importantly, the color signals extracted under different readout modes are the same because the phase difference of O and E light is essentially generated by the MA region and remains unchanged in both transmission and reflection readout modes (Figure S14B, Supporting Information).…”

Fano resonant optical coatings platform for full gamut and high purity structural colors

“…Durability is a common issue for applications of optical coatings. Durable FROCs could be made using ceramic materials 30 . We believe that FROCs are particularly suitable for colored solar thermal panels as they are efficient in absorbing the solar spectrum 16 while reflecting an on demand, narrowband color.…”

Fano Resonant Optical coatings platform for Full Gamut and High Purity Structural Colors

“…Because thin lm structural coloring in general has lower spatial resolution compared to nanostructures based structural coloring, the latter remains advantageous for high density coloring. Durable FROCs can be made with ceramic materials 20 . We believe that FROCs are particularly suitable for colored solar thermal panels as they are e cient in absorbing the solar spectrum 16 while re ecting an on demand, narrowband color.…”