Self-Assembly of Carbon Black/AAO Templates on Nanoporous Si for Broadband Infrared Absorption

Abstract

Broadband absorption in the mid-infrared region is of significance for wide applications, such as photo/thermal detection, infrared stealth, and thermal imaging. Recently, metal-based plasmonic absorbers have been developed in the mid-infrared region. However, the fabrication cost, thickness, and bandwidth of these absorbers applied in aerospace still need to be improved. In this study, we propose and experimentally demonstrate a large-area, rather thin, metal-free absorber with broadband mid-infrared absorption based on a low-cost self-assembly process. The metal-free absorber is fabricated by spraying carbon black nanoparticles onto 5 μm-thick transferrable anodic aluminum oxide (AAO) templates on nanoporous Si graded-index films, which are fabricated by ion irradiation. Experimental results show that the average absorbance can reach 97.5% in the range of 2.5–15.3 μm. Full-wave numerical simulations show that the electromagnetic fields are greatly enhanced into pores, as these random carbon black particles serve as scatter centers and couple light into 5 μm-thick AAO templates, enhancing the interaction of light with carbon black significantly, and reveal that the high-performance broadband absorption is attributed to the light-trapping effect. The significant light absorption combined with a low-cost, high-production self-assembly technique suggests that the absorber can be used in the fields of optoelectronics and integrated photonics.

Recent Advances in Nanoporous Anodic Alumina: Principles, Engineering, and Applications

“…NAA templatebased fabrication enables tailor-engineering of a periodic structure, as demonstrated by Lim et al [216], where the fabrication of 2D Au nanodot single-lattices with different geometry is presented. There are many ways in which a material of interest can be introduced into NAA: Electrodeposition [217,218], salinization [206], inkjet printing [219], galvanic displacement [220], spraying [221], and polymerization [222]. With a precisely adjusted experimental setup, obtained structures feature an advanced morphology and can mix several functionalities or elements (Figure 17) [223].…”

Flexible Daytime Radiative Cooling Enhanced by Enabling Three-Phase Composites with Scattering Interfaces between Silica Microspheres and Hierarchical Porous Coatings

“…In most of these application scenarios, daytime radiative cooling (DRC) is urgently needed rather than nocturnal cooling, yet it is also more challenging since solar radiation generally far exceeds thermal emission during the day. Many advanced photonic structures have already been developed toward maximizing both the solar reflectivity and thermal emissivity simultaneously, such as multilayered films, − nanoparticle-based composite materials, − and porous media coatings. − ,− For example, Zhai et al fabricated a kind of nonporous two-phase (i.e., microsphere-phase and polymer-phase) hybrid metamaterials in a roll-to-roll manner, which exhibits a strong emissivity (∼0.93) in the mid-infrared regime but a high transmittance in the visible range; with the silver coating deposited as a back reflector, the solar reflectivity can be increased to ∼96% and thus yielding a cooling power of 93 W/m 2 at noontime . Although silver and other metal mirrors are widely employed in the radiative coolers, it is generally expensive and prone to cause light pollution in practical use due to specular reflection.…”

Controlling the Multiscale Topography of Anodized Aluminum Oxide Nanowire Structures for Surface-Enhanced Raman Scattering and Perfect Absorbers

“…Self-aggregated nanowire structures have gained potential interest for future plasmonic-based on-chip devices. Owing to the drastically enhanced surface-to-volume ratio, thus-prepared AAO structures could be used as a plasmonic template for application in selective absorption/reflection, colorimetry, and surface-enhanced Raman scattering (SERS) in near-infrared (NIR) regime. − …”