Abstract
Certain bird species have evolved spectacular colors that arise from organized nanostructures of melanin. Its high refractive index (∼1.8) and broadband absorptive properties enable vivid structural colors that are nonsusceptible to photobleaching. Mimicking natural melanin structural coloration could enable several important applications, in particular, for noniridescent systems with colors that are independent of incidence angle. Here, we address this by forming melanin photonic crystal microdomes by inkjet printing. Owing to their curved nature, the microdomes exhibit noniridescent vivid structural coloration, tunable throughout the visible range via the size of the nanoparticles. Large-area arrays (>1 cm2) of high-quality photonic microdomes could be printed on both rigid and flexible substrates. Combined with scalable fabrication and the nontoxicity of melanin, the presented photonic microdomes with noniridescent structural coloration may find use in a variety of applications, including sensing, displays, and anticounterfeit holograms.
Highlights
Certain bird species have evolved spectacular colors that arise from organized nanostructures of melanin
Such natural structural coloration (SC) has inspired the development of engineered nanophotonic materials, which circumvent limitations of traditional coloration strategies based on pigments or dyes.[3,4]
To suppress such white background and improve color hue, researchers have incorporated lightabsorbing materials such as carbon black into colloidal NP assemblies.[17−19] An alternative approach, which avoids the need for black additives and thereby facilitates better control of the self-assembly process, uses NPs made of partially lightabsorbing materials, such as melanin
Summary
R.S. and M.J. conceived the original idea. R.S. carried out the material synthesis, characterization, inkjet printing, optical characterization, and interpreted the data. S.S. assisted in setting up the microspectroscopy setup and initial inkjet printing. S.G. contributed to angle-dependent spectroscopic measurements, and S.R. contributed to calculations and theoretical understanding. All work was coordinated by M.J. R.S. and M.J. wrote the manuscript through contributions of all authors. All authors has approved the final version of the manuscript. Notes The authors declare no competing financial interest
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