A set of empirical equations describing the observed colours of metal-anodic aluminium oxide-Al nanostructures

Cristina V Manzano; Jakob J Schwiedrzik; Gerhard Bürki; Laszlo Pethö; Johann Michler; Laetitia Philippe

doi:10.3762/bjnano.11.64

A set of empirical equations describing the observed colours of metal-anodic aluminium oxide-Al nanostructures

Beilstein J Nanotechnol. 2020 May 13:11:798-806. doi: 10.3762/bjnano.11.64. eCollection 2020.

Authors

Cristina V Manzano¹, Jakob J Schwiedrzik¹, Gerhard Bürki¹, Laszlo Pethö¹, Johann Michler¹, Laetitia Philippe¹

Affiliation

¹ Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Mechanics of Materials and Nanostructures, Feuerwerkerstrasse 39, CH-3602 Thun, Switzerland.

Abstract

Structural colours have received a lot of attention regarding the reproduction of the vivid colours found in nature. In this study, metal-anodic aluminium oxide (AAO)-Al nanostructures were deposited using a two-step anodization and sputtering process to produce self-ordered anodic aluminium oxide films and a metal layer (8 nm Cr and 25, 17.5 and 10 nm of Au), respectively. AAO films of different thickness were anodized and the Yxy values (Y is the luminance value, and x and y are the chromaticity values) were obtained via reflectance measurements. An empirical model based on the thickness and porosity of the nanostructures was determined, which describes a gamut of colours. The proposed mathematical model can be applied in different fields, such as wavelength absorbers, RGB (red, green, blue) display devices, as well as chemical or optical sensors.

Keywords: anodic aluminium oxide (AAO) films; anodization; plasmonic effects; polar coordinates; reflectance; structural colours.

Grants and funding

C.V.M. would like to acknowledge funding support from the Marie Curie Actions cofund program of the EU's Seventh Research Framework Program (FP7).