Directing near-infrared photon transport with core@shell particles

Abstract

Directing the propagation of near-infrared radiation is a major concern in improving the efficiency of solar cells and thermal insulators. A facile approach to scatter light in the near-infrared region without excessive heating is to embed compact layers with semiconductor particles. The directional scattering by semiconductor@oxide (core@shell) spherical particles (containing Si, InP, TiO2, SiO2, or ZrO2) with a total radius varying from 0.1 μm to 4.0 µm and in an insulating medium at a low volume fraction is investigated using Lorenz–Mie theory and multiscale modeling. The optical response of each layer is calculated under irradiation by the Sun or a blackbody emitter at 1180 K. Reflectance efficiency factors of up to 83.7% and 63.9% are achieved for near-infrared solar and blackbody radiation in 200 µm thick compact layers with only 1% volume fraction of bare Si particles with a radius of 0.23 µm and 0.50 µm, respectively. The maximum solar and blackbody efficiency factors of layers containing InP particles were slightly less (80.2% and 60.7% for bare particles with a radius of 0.25 µm and 0.60 µm, respectively). The addition of an oxide coating modifies the surrounding dielectric environment, which improves the solar reflectance efficiency factor to over 90%, provided it matches the scattering mode energies with the incident spectral density. The layers are spectrally sensitive and can be applied as a back or front reflector for solar devices, high temperature thermal insulators, and optical filters in gradient heat flux sensors for fire safety applications.

Electromagnetic response and optical properties of anisotropic CuSbS2 nanoparticles

“…Our results in Publications II-IV show that the addition of a thin oxide layer to shift the resonances can be used to match the solar reflectance efficiency factor to over 90% with the incident spectral density [168].…”

Silica-Silicon Composites for Near-Infrared Reflection: A Comprehensive Computational and Experimental Study

“…Beginning around at 4.5 µm, there is expected to be a pronounced effect from the absorption from the Si-O stretching modes within the medium. Absorption by oxides have previously been considered in the shell of semiconductor particles coated with an oxide layer [11,34]. Indeed, FTIR shows strong absorption in this region (Figure S5 [24]).…”

“…Composite compacts embedded with low volume fraction of low bandgap semiconductor microparticles, such as silicon or germanium, are predicted to reflect over 80% of NIR solar radiation [11] and up to 65% of blackbody radiation [12]. The strong reflectance is achieved with much lower volume fraction (1%) than compacts of similar thickness containing hBNplatelets at 50% volume fraction [13].…”

Core‐Shell Micro‐ and Nano‐Structures for The Modification of Light‐Surface Interactions

“…In a simulation study, Conley and team modelled several semiconductor@oxide spheres and characterized their reflectance efficiency under NIR irradiation. [ 63 ] Two low bandgap semiconductor materials (Si and InP) and three metal oxide materials (TiO 2 , SiO 2 and ZrO 2 ) with promising NIR reflectance characteristics were selected for the study. The diameters of the core‐shell spherical particles were varied from 0.2–8.0 µm.…”