Colloidal self-assembly based all-metal metasurface absorbers to achieve broadband, polarization-independent light absorption at UV–Vis frequencies

Abstract

Here, we demonstrate a straightforward colloidal self-assembly strategy to fabricate metasurface absorbers (MAs) with efficient broadband light absorption from ultraviolet (UV) to visible (Vis) spectral range. In this study, high-index faceted colloidal Au nanocrystals (NCs), i.e., Au icosidodecahedron with active surface plasmonic modes, are innovatively designed as the meta-atoms, while a facile electrostatic self-assembly progress is implemented to arrange these meta-atoms onto a gold reflecting film, resulting in MAs with all-metal structures. Optical characterizations show that the well-designed MAs with a 28–32% surface coverage of Au meta-atoms exhibit an average light absorption above 94% within the wavelengths ranging from 200 to 600 nm. Moreover, the particular absorption behaviors of the designed MAs are inherently polarization-independent for a broad range of incident angles (0–45°) owing to the ultrathin structure and topological symmetry of the devices. It has been inferred that the positive localized surface plasmon and gap plasmon resonances excited from the adjacent Au meta-atoms and gold film are critical for self-assembled MAs with excellent absorbing performances. Overall, this work provide an alternative and simple pathway for the construction of scalable and practical UV–Vis MAs, which may facilitate the high-frequency optical applications of thermophotovoltaics, photoelectric devices and photochemical systems.