Broadband perfect absorbers have been intensively researched for decades because of their near-perfect absorption optical property that can be applied to diverse applications. Unfortunately, achieving large-scale and heat-tolerant absorbers has been remained challenging work because of costly and time-consuming lithography methods and thermolability of materials, respectively. Here, we demonstrate a thermally robust titanium nitride broadband absorber with >95% absorption efficiency in the visible and near-infrared region (400–900 nm). A relatively large-scale (2.5 cm × 2.5 cm) absorber device is fabricated by using a fabrication technique of multiple-patterning colloidal lithography. The optical properties of the absorber are still maintained even after heating at the temperatures >600 ∘C. Such a large-scale, heat-tolerant, and broadband near-perfect absorber will provide further useful applications in solar thermophotovoltaics, stealth, and absorption controlling in high-temperature conditions.
Block copolymers (BCPs) with various nanostructures such as spheres, cylinders, gyroid, and lamellae, have received great attention for their application in nanolithography through nanopattern transfer to substrates. However, the fabrication of diverse geometries, shapes and sizes of nanostructure on a single substrate at the desired position could not be achieved because the nanostructure based on BCPs is mainly determined by the volume fraction of one block. Here, we synthesize polystyrene−hv−poly(methyl methacrylate) copolymer (PS−hv−PMMA), which contains a photocleavable linker at the junction point between PS and PMMA blocks. After vertically oriented PMMA cylindrical nanodomains in a thin film on a substrate were obtained, dual nanopatterns composed of high-density array of nanodots and nanoholes were successfully fabricated at the desired area on a single substrate using selective irradiation with a mask. The dual nanopatterns could be used to prepare metal (or metal oxide) nanostructure arrays consisting of both nanodots and nanoholes, which are utilized for smart sensors capable of simultaneously detecting two independent molecules on nanodots and nanoholes.
We investigated the morphology of lamellae-forming polystyrene-block-poly(methyl methacrylate) copolymer (PS-b-PMMA) confined in asymmetric hemisphere nanocavities which were
prepared by oblique angle deposition of gold with various thicknesses.
When the thickness of the deposited gold layer (t
Au) was 0.5L
0 of PS-b-PMMA (L
0 is the lamellar domain
spacing of PS-b-PMMA in bulk), concentric lamellar
patterns were formed on the top surface of the nanocavities. Interestingly,
at t
Au = 1L
0, WiFi-like nanopatterns were observed on the top surface. This is
because of the reduction of dislocations of PS and PMMA lamellar microdomains
near the center of the nanocavity. The experimentally observed morphologies
are consistent with prediction by self-consistent field theory. In
addition, the inner wall of the hemispherical nanocavity was modified
by grafting three different polymer brushes (PS, PMMA, and PS-r-PMMA) to change the affinity to each block. When the nanocavity
was grafted by PMMA, WiFi-like nanopatterns were observed. On the
other hand, laterally stacked U-shaped nanopatterns were formed in
a nanocavity grafted by PS-r-PMMA with neutral affinity
to PS and PMMA. We also fabricated an array of silver WiFi-like nanopatterns
composed of laterally stacked split-ring resonators after selective
silver deposition only on the PS microdomains. They showed unique
plasmonic resonances depending on the polarization angle of incident
light in near-infrared (NIR) wavelengths. The nanopatterns with broken
symmetry obtained in this study can be used in advanced optical devices
for structural coloration and optical anticounterfeiting.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.