97 percent light absorption in an ultrabroadband frequency range utilizing an ultrathin metal layer: randomly oriented, densely packed dielectric nanowires as an excellent light trapping scaffold

Abstract

In this paper, we propose a facile and large scale compatible design to obtain perfect ultrabroadband light absorption using metal-dielectric core-shell nanowires. The design consists of atomic layer deposited (ALD) Pt metal uniformly wrapped around hydrothermally grown titanium dioxide (TiO) nanowires. It is found that the randomly oriented dense TiO nanowires can impose excellent light trapping properties where the existence of an ultrathin Pt layer (with a thickness of 10 nm) can absorb the light in an ultrabroadband frequency range with an amount near unity. Throughout this study, we first investigate the formation of resonant modes in the metallic nanowires. Our findings prove that a nanowire structure can support multiple longitudinal localized surface plasmons (LSPs) along its axis together with transverse resonance modes. Our investigations showed that the spectral position of these resonance peaks can be tuned with the length, radius, and orientation of the nanowire. Therefore, TiO random nanowires can contain all of these features simultaneously in which the superposition of responses for these different geometries leads to a flat perfect light absorption. The obtained results demonstrate that taking unique advantages of the ALD method, together with excellent light trapping of chemically synthesized nanowires, a perfect, bifacial, wide angle, and large scale compatible absorber can be made where an excellent performance is achieved while using less materials.

Lithography‐Free Random Bismuth Nanostructures for Full Solar Spectrum Harvesting and Mid‐Infrared Sensing

“…For L < 200 nm, only the dominant mode is excited (which is the first‐order longitudinal mode) and near unity absorbance is acquired in a narrow spectral range. As the rod length becomes larger, multiple absorbance modes are supported with the design and superposition of these modes leading to a broadband near unity absorbance, which are in line with the previous findings . Moreover, the absorbance strength continuously grows stronger with increasing nanorod lengths as expected because the excited modes are mainly longitudinal modes, and new modes are excited with increased nanorod lengths.…”

“…2020, 8,1901203 www.advopticalmat.de findings. [34] Moreover, the absorbance strength continuously grows stronger with increasing nanorod lengths as expected because the excited modes are mainly longitudinal modes, and new modes are excited with increased nanorod lengths. Furthermore, a slight redshift of the resonance wavelengths occurs in longer nanorods.…”

“…Recent studies have demonstrated that randomly distributed and disordered structures can achieve on par performance with periodically ordered structures, [26][27][28][29][30][31][32][33][34][35] or can even surpass them. However, the chemical processes that are used in the fabrication of these devices require controlling of various parameters, such as the etching time and temperature.…”

Large‐Area, Ultrathin Metasurface Exhibiting Strong Unpolarized Ultrabroadband Absorption

“…A black body that absorbs broadband omnidirectional radiation is an ideal absorber, which has applications in energy harvesting, photodetectors, photothermal energy generation, and concealment . Film‐based absorbers, such as multiple pairs of stacked metal/dielectric films or multilayer‐stacked films, are suitable for the large‐area fabrication.…”

Lithography-free, manganese-based ultrabroadband absorption through annealing-based deformation of thin layers into metal–air composites

“…Therefore, it has always been very desirable to come up with lithography-free, cost-effective, and easy-to-fabricate structures. Some of the designs for lithography-free absorbers are based on planar MIM cavities [6,7], metal-insulator multilayer stacks [8], chemically synthesized metal-coated dielectric nanowires [9], random nanopillars [10], and etching-based random pyramids formed in doped Silicon wafers [11]. In addition, lithography-free absorbers without a broadband response are also of high interest, and they cover a wide range of crucial applications such as filtering [12], real-time tuning [13], and bio-sensing [14].…”