posted on 2018-10-18, 00:00authored byZengyao Wang, Bin Ai, Ziwei Zhou, Yuduo Guan, Helmuth Möhwald, Gang Zhang
Hollow
nanocone array (HNCA) films (cm × cm), composed of
two Ag and Au nanoshells, are fabricated via a low-cost
and efficient colloidal lithography technique. The relative position
of the Ag and Au nanoshells can be controlled to generate various
chiral asymmetries. A pronounced chiroptical response is observed
in the ultraviolet–visible region with the anisotropy factor
up to 10–1, which is rooted in the asymmetric current
oscillations and electric field distributions. Beyond previous reports
on plasmonic chiral metamaterials, the HNCA can be free-standing and
further transferred to other functional and flexible substrates, such
as polydimethylsiloxane (PDMS), highly curved surfaces, prepatterned
films, and hydrogels, while keeping the original features. The good
transferability would make HNCA more flexible in specific applications.
Furthermore, the chiral HNCAs offer a series of chiral resonance cavities,
which are conducive for the research of chiral sensing, confinement,
chiral signal transmission, and amplification. Overall, this work
provides a scalable metamaterial to tune the plasmonic chiral response,
and HNCA would be a promising candidate of the components in chiral
optical devices and sensors.