Cooling is a key technology of our modern life. A device capable of efficient sub-ambient daytime cooling without the need for an external power input would considerably lower our overall energy consumption. Nature offers a chance to off-load heat directly into the cold outer space via the so-called “sky window”: a wavelength range from 8 – 13 μm, where our atmosphere is transparent. Inspired by examples from nature, namely the white beetle and the Saharan silver ant, this proposal aims to develop materials that selectively emit thermal energy into this sky window wavelength range, and scatter and reflect radiation of all other wavelengths, particularly visible and near-infrared (300 nm – 2.5 μm) irradiated by the sun.Top-down direct write lithography will be combined with controlled bottom-up colloidal self-assembly to create hierarchically structured systems fully addressing these stringent optical properties, which cover the entire spectral range from 300 nm – 20 μm.
In combination with polymers and metallic nanostructures these hybrid devices will have finely adjusted and even externally tuneable optical properties, allowing for a switching of the cooling capacity. Finite element modelling will add a deeper understanding of the structure-property relationships and yield optimum design rules. Based on this fundamental work, VISIRday will provide concepts for functional paints and fibres - advanced materials that enable passive daytime cooling as a new green energy technology.
(Figures designed by Daniela Leitner (c))
- ERC Starting Grant call 2016
- start date: March 1st 2017
- This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 714968