New glass technology can selectively block light, heat

New glass technology could let in light while keeping out heat.

By Cameron Jewell

15 August 2013 — Researchers in the US have developed a smart glass that can switch between blocking light, heat or both, depending on how much voltage is applied. The technology could have applications in buildings, with façades letting in natural light while moderating heat transfer to save on energy costs.

The article, Tunable near-infrared and visible-light transmittance in nanocrystal-in-glass composites, published in Nature, said that modulation of visible and near-infrared radiation was considered a “holy grail” for reducing the energy needed to light and thermally regulate building interiors.

The process allowing the glass to change its light and heat transmittance is called electrochromism, a reversible change of optical transmittance in response to electrochemical charging and discharging.

The material used by the researchers incorporated two functional components that could be manipulated by controlling the voltage applied to the glass.

By linking tin-doped indium oxide nanocrystals that can block near-infrared light to a niobium oxide glass matrix that can modulate visible light transmission, the researchers were able to control optical characteristics by varying the voltage.

They were able to create three states: fully transparent; blocking near-infrared light; and blocking both visible and near-infrared light.

The researchers said the glass could have application in buildings, controlling how solar radiation passed into buildings to reduce energy costs.

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