Smart windows contain glass that controls the transmission of light. When subjected to an electric field, the glass becomes dark and blocks the light while keeping a clear view through them.

Anna Llordés, The Molecular Foundry, Berkeley, USA, and colleagues developed a nanoparticle-based material that can be used to further enhance the performances of these windows. By covalently linking indium tin oxide nanocrystals in a glassy matrix of niobium oxide, the researchers obtained a composite material where the transmission of daylight (visible light) and solar heat (near-infra red light) are controlled independently from each other. This means that, owing to the molecular interactions occurring at the interphase of its two components, the novel composite can block heat but, at the same time, absorb light.

The new material could be used to produce smart windows that maximize energy savings and customer comfort by blocking heat without becoming dark.

• Tunable near-infrared and visible-light transmittance in nanocrystal-in-glass composites,
  Anna Llordés, Guillermo Garcia, Jaume Gazquez, Delia J. Milliron,
  Nature 2013, 500, 323–326.
  DOI: 10.1038/nature12398