Structure color Photonic Structures: Discovery, Replication & Application Yunyun Dai Photonics Group Department of Electronics and Nanoengineering School of Electrical Engineering Aalto University
Outline Introduction Natural color generation Photonic crystals in nature Properties of structure colors Amorphous photonic structure colors Artificial structure colors Inversion from templates Self-assembly Plasmonic coloration Conclusions
What is COLOR? Color is the characteristic of human visual perception described through color categories, with names such as red, yellow, green, blue, or purple. This perception of color derives from the stimulation of cone cells in the human eye by electromagnetic radiation in the reflected (or luminous) light spectrum of light from objects. (From wikipedia)
Color generation Ultra-violet 400 nm 500 nm 600 nm 700 nm infrared Pigment color Bioluminescence Structure color Jellyfish parrot
Pigment color Selective absorption Tulips from Holland Cafe terrace at night By van gogh Eyeshadow from NARS
Bioluminescence Firefly Jellyfish Chemical reaction: A + B C + Photon
Structural color From interactions between light and photonic structures Interference Diffraction Scattering
Photonic crystals Photonic band structure For some frequency range, a photonic crystal prohibits the propagation of electromagnetic waves traveling, we say that the crystal has a photonic band gap.
Mechanism for structural coloration 1D photonic crystal interference The condition for constructive interference For n1 < n < n2 or n1 >n>n2, is given by 2nd cosθ =m λ
Photonic crystals (PCs) in nature 1D PCs 2D PCs 3D PCs FCC Parker et al., JEB 1998 Zi et al., PNAS 2003 Welch et al., PRE 2007 With both short- and long-range order Iridescent
Photonic crystals (PCs) in nature Brazail morpho P. Vukusic, Proc. R. Soc. (1999) Hybrid structures Indonesian butterfly P. Vukusic, Nature (2000)
Properties of structural colors
Properties of structural colors Iridescence Color varying with different observation angles Pigeon H.Yin, Phys. Rev. E (2006)
Properties of structural colors Polarization dependence V.Sharma, Science (2009)
Properties of structural colors Active color change Many vertebrates can rapidly change color By modifications of brightness pigmental By tuning skin hue structural
Active color change in chameleons J. Teyssier, nature comm. (2015)
Active color change in chameleons Distance among crystals changes from relaxed to excited skin.
Amorphous photonic structure colors
Classification of photonic structures Crystalline Amorphous Random Periodic Amorphous Random Long-range order Yes No No Short-range order Yes Yes No Structural color Periodic Amorphous Random Photonic crystal Iridescence Yes No No
Amorphous photonic crystals in nature Amorphous diamond structure Random close-packing Yin et al., PNAS 109, 10798 (2012) With only short-range order B.Q. Dong et al., Opt. Express 2010 2 μm Non-iridescent
Amorphous photonic crystals in nature Greenish white stripes Dull metallic color 20 μm Beetle Anoplophora graafi belongs to a family of Cerambycidae (longhorn beetles), found in Borneo rainforest of Indonesia and Malaysia. B.Q. Dong, Opt. Express (2010) Blue Green Yellow Red
Pointillistic Color Mixing A Sunday Afternoon on the Island of La Grande Jatte Georges Seurat
Longhorn beetles Spectra and structure of Colored Scales Diverse coloration due to size scaling 200 nm 5 μm 200 nm
Longhorn beetles Structure analysis Photonic pseudo-gaps 3 Spectral content (arb. units) 1 1.38 1.56 Chitin spheres N=1.56 Pseudogap RDF 2 1 1 2 3 0 0 1 2 3 4 5 r / d 4 0.0 0.2 0.4 0.6 0.8 f d/c Photon Density of States (PDOS) of a system describes the number of photonic states available at each frequency.
Artificial structure color
Fabrication methods Inversion from templates Easy, low-cost limited by templates Self-assembly Low-cost Not easy to attain disordered structures Nanofabrication Expensive Easy for 2D but difficult for 3D
Inversion from templates Beetle Sphingnotus mirabilis 100 μm Reflection Broad peak Transmission 20 μm Spinodal decomposition structure Y. F. Zhang et al., Bioinspir. Biomim (2013)
Inversion from templates Inverted SiO 2 0.6 Inverted Al 3 O 2 Reflectance 0.4 0.2 400 500 600 700 Wavelength (nm)
Potential applications in photonics Enhance light extraction from OLED Nature photonics 4, 222 (2010) Antireflection coatings Science 283, 520 (1999)
Self-assembly Single-size spheres Single-size spheres with ions Dual-size spheres: 226 nm & 271 nm FCC Electrostatic repulsive force Carbon [wt%] P. D. García et al., Adv. Mater. 19, 2597 (2007) J. D. Foster et al., Adv Mater. 22, 2939 (2010) Photonics Lecture Micronova, Espoo 27,4,2017
Self-assembly Using cuttlefish ink as an additive Dried cuttlefish ink Ink particles ~ 110 nm Absorption (%) 100 98 96 94 92 90 300 400 500 600 700 800 90010001100 Wavelength (nm) Advantages Non-spherical shape, easy to attain amorphous structures Broadband absorption, enhance color visibility
Self-assembly Simple procedure: Mixing PS spheres and ink particles in water Drop onto a substrate Just wait for drying Ink particles 500 nm 500 nm 200-nm PS spheres alone 200-nm PS spheres + ink particles
Self-assembly Color palette
Plasmonic coloration notre dame de paris
Plasmonics and plasmonic coloration Ebbesen et al., Nature 391, 667 (1998) Interactions between light and metal particles X..M. Goh et al., Nature Comm. (2014)
Plasmonic color laser printing X. L. Zhu et al., Nature Nanotech. (2016)
Plasmonic color laser printing X. L. Zhu et al., Nature Nanotech. (2016)
Printing color at optical diffraction limit K. Kumar et al., Nature Nanotech. (2012)
Tunable plasmonic color generation D. Franklin et al., Nature Comm. (2015)
Conclusion Photonic structure colors Iridescence, Metallic color, fadeless, tunable color.. Artificial plasmonic colors Active printing, tunable colors..
Thanks for your attention!