Spectrally-selective gold nanorod coatings for window glass

Abstract

The unique optical properties of gold nanorods, which exhibit tuneable absorption as a function of their aspect ratio, suggest that they might have potential applications in coatings for solar control on windows. Here we explore the properties of coatings produced by attaching gold nanorods to the surface of glass. Such coatings can attenuate solar radiation effectively, even at very low gold contents, but the figure-of-merit, T vis /T sol , of our experimental coatings was close to unity, indicating that they are not spectrally selective, However, calculations are presented to show how coatings comprised of a blend of rods with aspect ratios of greater than 3 can produce coatings with T vis /T sol of up to at least 1.4. The maximum value possible for perfectly spectrallyselective coating in sunlight is 2.08. Unfortunately, the practical realization of such coatings requires the further development of reliable methods to scale up the production of gold nanorods of longer aspect ratios. Gold Bulletin 2006 • 39/4 156

Preparation of Electrically Conductive Au Thin Films by Colloid Sedimentation

“…[2][3][4][5] Au thin films on glass also have the potential to be used as transparent conductive electrodes (TCEs) in solar cells, and infrared reflective coatings for architectural windows. 6,7 Different applications require different properties of the Au thin films. For example, they must be continuous in order to act as conductive corrosion-protection coatings for electrical contacts in electronic devices.…”

Plasmon resonance and electric field amplification of crossed gold nanorods

“…The transmission spectra of both types of coating will be characterized by a strong absorption peak, the position of which is tunable, as shown here for the crossed-rods and elsewhere e.g. [8] for the randomly oriented individual rods. However, a coating of rods or crossedrods that are aligned will additionally show a sensitivity to the direction of both the electric and magnetic fields of the light, while a coating made from randomly oriented rods or crossed rods will not.…”

“…However, a coating of rods or crossedrods that are aligned will additionally show a sensitivity to the direction of both the electric and magnetic fields of the light, while a coating made from randomly oriented rods or crossed rods will not. Although spectral selectivity can be obtained by mixing together ordinary nanorods of different aspect ratio, which may have applications in solar screening [8], crossed-rod structures may be attractive in applications that engage with some aspect of the polarization of the incident light or the electric field generated around the targets. For example, a polarizing filter created by a crossed-rod array would have the attributes of being active over only a narrow range of wavelengths, and also have a rotational sensitivity that varies at double the rate of conventional polarizing filters.…”

“…This has encouraged investigations into the application of nanorods in medicine and biology [6,7], spectrally selective coatings [8], and optical data storage [9]. Another interesting property of nanorods, one that is absent from nanospheres or nanoshells, is a strong dependence of the optical properties on the polarization of the incident light [4].…”

Nanophotonics-enabled smart windows, buildings and wearables

“…They can strengthen, shift and extend the width of scattering peaks or act as antireflecting outer layer to enhance absorption or transmission in the resonant nanostructures below. Doping oxides, polymers or polymer layers with noble metal nanoparticles is a common way to achieve sharp plasmonic resonance at visible and, for some shapes, near-IR wavelengths [66][67][68]. Nevertheless, these are not well suited for use in building windows and skylights for reasons of durability and cost, and because they often reduce light input.…”