Floating solid-state thin films with dynamic structural colour

Thin-film architectures are a staple in a wide range of technologies, such as semiconductor devices, optical coatings, magnetic recording, solar cells and batteries. Despite the industrial success of thin-film technology, mostly due to the easy fabrication and low cost, a fundamental drawback remains: it is challenging to alter the features of the film once fabricated. Here we report a methodology to modify the thickness and sequence of the innermost solid-state thin-film layers. We start with a thin-film stack of amorphous iron oxide and silver. By applying a suitable voltage bias and then reversing it, we can float the silver layer above or below the oxide layer by virtue of the migration of silver atoms. Scanning transmission electron microscopy reveals various sequences and thicknesses of the silver and oxide layers achieved with different experimental conditions. As a proof-of-principle, we show a dynamic change of structural colours of the stack derived from this process. Our results may offer opportunities to dynamically reconfigure thin-film-based functional nanodevices in situ. A silver layer can be made to float either above or below an oxide layer in a thin-film architecture by applying a voltage bias.

Automated summary

A method to modify the thickness and sequence of innermost solid-state thin-film layers has been reported, allowing for dynamic changes in structural colors of the stack. By applying a voltage bias, a silver layer can be made to float either above or below an oxide layer in a thin-film architecture, potentially providing opportunities for dynamically reconfiguring thin-film-based functional nanodevices in situ.