We
demonstrate tunable structural color patterns that span the
visible spectrum using atomic layer deposition (ALD). Asymmetric metal–dielectric–metal
structures were sequentially deposited with nickel, zinc oxide, and
a thin copper layer to form an optical cavity. The color response
was precisely adjusted by tuning the zinc oxide (ZnO) thickness using
ALD, which was consistent with model predictions. Owing to the conformal
nature of ALD, this allows for uniform and tunable coloration of non-planar
three-dimensional (3D) objects, as exemplified by adding color to
3D-printed parts produced by metal additive manufacturing. Proper
choice of inorganic layered structures and materials allows the structural
color to be stable at elevated temperatures, in contrast to traditional
paints. To print multiple colors on a single sample, polymer inhibitors
were patterned in a desired geometry using electrohydrodynamic jet
(e-jet) printing, followed by area-selective ALD in the unpassivated
regions. The ability to achieve 3D color printing, both at the micro-
and macroscales, provides a new pathway to tune the optical and aesthetic
properties during additive manufacturing.
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