Numerical Study of an Efficient Solar Absorber Consisting of Metal Nanoparticles

Visible and Near-Infrared Broadband Absorber Based on Ti3C2Tx MXene-Wu

A high absorption broadband absorber based on MXene and tungsten nanospheres in visible and near-infrared bands is proposed. The absorber has a maximum absorption of 100% and an average absorption of 95% in the wavelength range of 400-2500 nm. The theoretical mechanism and parameter adjustability of the absorber are analyzed by FDTD solutions. The results show that the structural parameters can effectively adjust the absorption performance. The good absorption performance is due to the action of the local surface plasmon resonance coupling with the gap surface plasmon resonance and Fabry-Perot resonance. The simulation results show that the absorber is insensitive to the polarization and oblique incidence angle of incident light, and that high absorption and broadband can be maintained when the oblique incidence angle is up to 60°.

Structure of Randomly Distributed Nanochain Aggregates on Silicon Substrates: Modeling and Optical Absorption Characteristics

Nanoparticle aggregate structures allow for efficient photon capture, and thus exhibit excellent optical absorption properties. In this study, a model of randomly distributed nanochain aggregates on silicon substrates is developed and analyzed. The Gaussian, uniform, and Cauchy spatial distribution functions are used to characterize the aggregate forms of the nanochains and their morphologies are realistically reconstructed. The relationships between the structural parameters (thickness and filling factor), equivalent physical parameters (density, heat capacity, and thermal conductivity), and visible absorptivity of the structures are established and analyzed. All the above-mentioned parameters exhibit extreme values, which maximize the visible-range absorption; these values are determined by the material properties and nanochain aggregate structure. Finally, Al nanochain aggregate samples are fabricated on Si substrates by reducing the kinetic energy of the metal vapor during deposition. The spectral reflection characteristics of the samples are studied experimentally. The Spearman correlation coefficients for the calculated spectral absorption curves and those measured experimentally are higher than 0.82, thus confirming that the model is accurate. The relative errors between the calculated visible-range absorptivities and the measured data are less than 0.3%, further confirming the accuracy of the model.

Metastable Atomic Layer Deposition: 3D Self-Assembly toward Ultradark Materials

Black body materials are promising candidates to meet future energy demands, as they are able to harvest energy from the total bandwidth of solar radiation. Here, we report on high-absorption near-blackbody-like structures (>98% for a wide solar spectrum range from 220 to 2500 nm) consisting of a silica scaffold and Ag nanoparticles with a layer thickness below 10 μm, fabricated using metastable atomic layer deposition (MS-ALD). Several effects contribute collectively and in a synergistic manner to the ultrahigh absorption, including the pronounced heterogeneity of the nanoparticles in size and shape, particle plasmon hybridization, and the trapping of omnidirectionally scattered light in the 3D hierarchical hybrid structures. We propose that, in the future, MS-ALD needs to be considered as a simple and promising method to fabricate blackbody materials with excellent broadband absorption.