  The fabrication of functional metamaterials with extreme feature resolution
finds a host of applications such as the broad area of surface/light
interaction. Non-planar features of such structures can significantly enhance
their performance and tunability, but their facile generation remains a
challenge. Here, we show that carefully designed out-of-plane nanopillars made
of metal-dielectric composites integrated in a metal-dielectric-nanocomposite
configuration, can absorb broadband light very effectively. We further
demonstrate that electrohydrodynamic printing in a rapid nanodripping mode, is
able to generate precise out-of-plane forests of such composite nanopillars
with deposition resolutions at the diffraction limit on flat and non-flat
substrates. The nanocomposite nature of the printed material allows the
fine-tuning of the overall visible light absorption from complete absorption to
complete reflection by simply tuning the pillar height. Almost perfect
absorption (~95%) over the entire visible spectrum is achieved by a nanopillar
forest covering only 6% of the printed area. Adjusting the height of individual
pillar groups by design, we demonstrate on-demand control of the gray scale of
a micrograph with a spatial resolution of 400 nm. These results constitute a
significant step forward in ultra-high resolution facile fabrication of
out-of-plane nanostructures, important to a broad palette of light design
applications. nanostructures, important to a broad palette of light design
applications.
