Wednesday, December 28, 2011

Industry News: Material Offers New Hope for Developing Smart Windows

According to a new report, Smart Windows are expected to play a big role in energy-efficient homes.

The idea is that they will allow light in while keeping the heat out. One material being considered for its potential to help create Smart Windows is known as Vanadium dioxide (VO2). This unique material has the ability to transition from a transparent semi-conductive state at low temperatures, allowing infrared radiation through, to an opaque metallic state at high temperatures, while still allowing visible light to get through.

The report says that to date, VO2 hasn't been considered to be particularly suited for large-scale practical smart-window applications due to its low luminous transmittance and solar modulating ability. Strategies to improve these properties, for instance through doping or composites, have resulted in trade-offs between the luminous transmittance and thermo-chromic properties.

The report goes on to say that researchers in China, however, have now developed a process that can prepare VO2 thin-films with a controllable polymorph and morphology (including grain size and porosity). Their results show that with increased porosity and decreased optical constants the performance of the VO2 films is enhanced, leading to a higher transmittance of visible light and improved solar modulating ability.

It is expected that VO2 thermo-chromic films will find special applications as a new generation of smart glass that can change infrared transmittance by responding to environmental temperature, while at the same time maintaining visible transparency.

This could result in a smart window that might be useful for locations with hot summers and cold winters.