Nanostructures that interact with light to produce structural color have a variety of applications in photonics, photovoltaics, photocatalysis, sensing and beyond. However, mass producing nanostructures with visible-wavelength structural color is often difficult, limiting their fabrication to the small scale and certain substrates.
Shapturenka et al. developed a scalable fabrication method to produce visible-wavelength nanostructures on any substrate. The authors combined standard nanofabrication techniques with an area-scalable nanosphere coating technique, known as Langmuir-Blodgett deposition, to create thin, partially suspended hole arrays of titanium dioxide (TiO2) on silicon. The arrays are quasi-ordered, meaning their holes are arranged in an imperfect honeycomb-like pattern that the close-packed nanosphere monolayers naturally form.
Source: “Quasi-ordered, sub-wavelength TiO2 hole arrays with tunable, omnidirectional color response,” by Pavel Shapturenka, Fabian Birkholz, Nicholas Isaac Zakaria, Steven P. DenBaars, and Michael J. Gordon, JVST: A (2020). The article can be accessed at https://doi.org/10.1116/6.0000328.
Combining dip coating of colloidal particles on a substrate with standard microelectronics fabrication techniques creates nanostructures with tunable structural color suited for a variety of applications.