Electrochromic Tech Enables Tunable Windows

Scientists from the University of Cincinnati claim to have developed a smart window technology that goes way beyond simple tinting. The group say that users can have control over brightness, colour temperature and opacity of the glass.

Working with researchers from HP, Merck and National Taiwan University, the team worked on adapting electrochromic technology. The intent was to scale the technology to cover a large area, without a significant cost increase.

Claimed to be cheap to manufacture, the final design can be applied to new or existing windows. Two glass substrates enclose a polymer layer, a set of electrodes and micro-replicated polymer nubs. The components are formed into a honeycomb patter. The electrophoretic dispersions are dual-particle, dual-coloured and controlled using two electrodes on the front and back substrates, as well as a third electrode on the perimeter of each unit cell.

UC’s Sayantika Mukherjee, who led the research, said, “”Basically, one colour has one charge… Another colour has another charge, and we apply voltage to repel or attract the colours into different positions”.

Four states can be switched between, or a mix of either of the four. They are clear, black or either of two complementary colours from the RGB/CMY colour sets.

Light transmission is said to be very high – as much as 90%, even when the windows are opaque. A contrast of 10:1, reflectance of 62% and transparency of 75% has been observed.

The research was published in Applied Optics: