Use of nanostructured alumina thin films in multilayer anti-reflective coatings

Abstract

A new method for modification of planar multilayer structures to create nanostructured aluminum oxide anti-reflection coatings is reported. The method is non-toxic and low-cost, being based on treatment of the coating with heated de-ionized water after the deposition of aluminum oxide. The results show that the method provides a viable alternative for attaining a low reflectance ARC. In particular, a low average reflectivity of ∼3.3% is demonstrated in a broadband spectrum extending from 400 nm to 2000 nm for ARCs deposited on GaInP solar-cells, the typical material used as top-junction in solar cell tandem architectures. Moreover, the process is compatible with volume manufacturing technologies used in photovoltaics, such as ion beam sputtering and electron beam evaporation.

Optical Performance Assessment of Nanostructured Alumina Multilayer Antireflective Coatings Used in III–V Multijunction Solar Cells

“…The method for nanostructuring the alumina surface is described in detail in reference. 21 The nominal structure of the nano-ARC and its cross-sectional scanning electron microscope image are shown in Figure 1 . The planar double-layer coating had the nominal structure of 50 nm TiO 2 /89 nm SiO 2 .…”

“…The nanostructuring of the amorphous alumina layer was achieved by treating the coating with heated deionized water (DIW). The method for nanostructuring the alumina surface is described in detail in reference . The nominal structure of the nano-ARC and its cross-sectional scanning electron microscope image are shown in Figure .…”

“…As an alternative, we proposed recently a simple, nontoxic, low-cost nanostructured multilayer ARC that is based on postdeposition treatment of planar amorphous alumina coatings with heated deionized water. , An advantage of this approach compared to similar kind of hybrid broadband ARC , is the reduced number of fabrication steps, as it does not need lithography and surface etching for patterning. The properties of the nanopattern can be controlled via film thickness and treatment time, and the hydrophobicity of the film can be increased with postprocess polymerization …”

Ice resistance of hydrophobic fluoropolymerized nanostructured alumina films for antireflective coatings

“…The use of nanostructured alumina antireflection coatings (ARC) have lately attracted scientific attention [1][2][3][4][5][6][7] owing to the simple and low-cost fabrication method, where an amorphous alumina thin film is nanostructured by a heated deionized water (DIW) treatment. The proven suitability of the method for general optics and applications [2,4] and solar cell coatings [1,3,5] makes this approach an appealing alternative to the established methods for fabricating nanostructured broadband ARCs, which generally speaking are more laborious [8][9][10][11][12][13][14][15][16]. On glass surfaces the nanostructured alumina ARCs have enabled an average transparency as high as 99% at visible wavelengths [1,2] on both sides coated substrates.…”

“…The proven suitability of the method for general optics and applications [2,4] and solar cell coatings [1,3,5] makes this approach an appealing alternative to the established methods for fabricating nanostructured broadband ARCs, which generally speaking are more laborious [8][9][10][11][12][13][14][15][16]. On glass surfaces the nanostructured alumina ARCs have enabled an average transparency as high as 99% at visible wavelengths [1,2] on both sides coated substrates. Furthermore, it is possible to combine the nanostructured alumina with conventional planar coatings to expand the spectral bandwidth of the low reflectivity and to match the refractive index to high index substrates such as semiconductors [2,3].…”