A large‐area, ultrathin metasurface perfect absorber (MSPA) based on coupled Mie resonances from integrated arrays of silicon (Si) and metallic pillars is reported. In contrast to previous structures and mechanisms, coupled Mie resonances are generated from two pillars of dissimilar materials (dielectric and metallic) within an ultrathin structure such that the Mie resonances of dielectric and metallic patterns occur complementarily at different wavelengths to realize broadband absorption over the entire visible wavelength band. Double‐beam interference lithography, reactive ion etching, and sputter coated depositions are utilized to fabricate the proposed MSPA. With an appropriate arrangement of the patterned geometry, an average polarization independent absorption of 0.975 (0.958, experiment) in the entire visible band (from 400 to 760 nm) is achieved and remains high (0.930, simulation, and 0.912, experiment) when the incident angle increases to 70°. The proposed MSPA is thus an effective way to realize a large‐area, ultrathin metasurface absorber with a relatively simple and easy to fabricate structure.

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The utilization of nonradiative decay of surface plasmons (SPs) in the form of hot electrons in metallic nanostructures has a great potential for applications in photovoltaics, photocatalysis, photodetection, and surface imaging. Unfortunately, the metallic nanostructures usually support only narrowband plasmon resonances; moreover, the hot-electron thermalization loss during the transport to Schottky interface and the confined momentum space for hot-electron injection into semiconductor together result in an inefficient internal quantum process. In this study, we propose and experimentally demonstrate a broadband super absorber based on the metallic nanorod arrays (NRs). Optically, the average absorption across the entire visible band is up to 0.8, which is over 16-fold enhancement of the planar reference. Electrically, the hot electrons are controlled to be preferentially generated near Schottky interface within the mean free path, relieving the severe hot-electron thermalization loss. Moreover, the three-dimensional Schottky junction provides much increased hot-electron momentum space for injection at the vertical surface. These optical and electrical benefits lead to over 30-fold enhancement in the IPCE (incident photon-to-electron conversion efficiency) relative to the reference. The IPCE can be up to 10.9% at E ph = 3.1 eV, which is close to the limit of the thick-film single-barrier hot-electron devices. The conformal NRs system provides a promising strategy to simultaneously improve the hot-electron generation, transport, and collection efficiencies and could be an outstanding candidate for efficient hot-electron optoelectronic and photocatalysis systems.

We report on a monolithic, all-metallic, and flexible metasurface perfect absorber [black nickel (Ni)] based on coupled Mie resonances originated from vertically stepped Ni nanopillars homoepitaxially grown on an Ni substrate. Coupled Mie resonances are generated from Ni nanopillars with different sizes such that Mie resonances of the stepped two sets of Ni nanopillars occur complementarily at different wavelengths to realize polarization-independent broadband absorption over the entire visible wavelength band (400-760 nm) within an ultra-thin surface layer of only 162 nm thick in total. Two-step double-beam interference lithography and electroplating are utilized to fabricate the proposed monolithic metasurface that can be arbitrarily bent and pressed. A black nickel metasurface is experimentally demonstrated in which an average polarization-independent absorption of 0.972 (0.961, experiment) in the entire visible band is achieved and remains 0.838 (0.815, experiment) when the incident angle increases to 70°.

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