Automatically Acquired Broadband Plasmonic-Metamaterial Black Absorber during the Metallic Film-Formation

TLDR

Broadband electromagnetic wave absorbers are highly desirable in applications such as solar‑energy harvesting, thermo‑photovoltaics, and photon detection. The study aims to efficiently produce ultrathin broadband absorbers with high yield and low cost. A sub‑10 nm meta‑surface film, automatically formed during metal‑film deposition, replaces the precisely designed metamaterial crystal in conventional metal–dielectric–metal absorbers. The absorber achieves >80 % absorbance over a 396 nm bandwidth (92 % FWHM) and an average 83 % absorbance from 370–880 nm, owing to particle plasmon resonances, near‑field coupling, and plasmon polaritons, demonstrating a simple, cost‑effective, large‑area fabrication method.

Abstract

Broadband electromagnetic wave absorbers are highly desirable in numerous applications such as solar-energy harvesting, thermo-photovoltaics, and photon detection. The aim to efficiently achieve ultrathin broadband absorbers with high-yield and low-cost fabrication process has long been pursued. Here, we theoretically propose and experimentally demonstrate a unique broadband plasmonic-metamaterial absorber by utilizing a sub-10 nm meta-surface film structure to replace the precisely designed metamaterial crystal in the common metal–dielectric–metal absorbers. The unique ultrathin meta-surface can be automatically obtained during the metal film formation process. Spectral bandwidth with absorbance above 80% is up to 396 nm, where the full absorption width at half-maximum is about 92%. The average value of absorbance across the whole spectral range of 370–880 nm reaches 83%. These super absorption properties can be attributed to the particle plasmon resonances and plasmon near-field coupling by the automatically formed metallic nanoparticles as well as the plasmon polaritons of the metal film with the induced plasmonic magnetic resonances occurring between the top meta-surface and the bottom metal mirror. This method is quite simple, cost-effective for large-area fabrication, and compatible with current industrial methods for microelectro-mechanical systems, which makes it an outstanding candidate for advanced high-efficiency absorber materials.