“Smart” windows reveal a sustainable future

BERKELEY, CALIF.» When it comes to a sustainable future, scientists aren’t seeing clearly.

Researchers have developed a new type of tinted “smart window” that generates electricity when darkened. The windows “can be automatically converted into a solar cell to generate electricity for us,” said Peidong Yang, a chemistry professor at UC Berkeley and researcher at Lawrence Berkeley National Laboratory in the Berkeley Hills who heads the team responsible for the discovery.

The new solar technology could potentially be used to power everything from electric vehicles to skyscrapers. Similar to solar panels currently in use, the windows would be able to generate electricity, send it to an inverter that changes that energy from a DC current to an AC current. That energy could then be used to power the building or car that houses the windows.

The smart windows are made from a mineral called perovskite. When the crystal is heated, its internal structure rearranges to darken the color of the glass, allowing it to absorb more light and create electricity. Scientists have known about the unique properties of perovskite for decades, but have only learned to harness them in the past five years.

While similar self-tinting windows on the market conserve energy passively by lowering the cost of air-conditioning, Yang’s innovation actively and reliably produces low amounts of electricity. Even after multiple transitions from light to dark, the smart windows are still able to produce electricity — something other versions have largely struggled to do.

“Typically technologies require at least a decade — if not more — to go from laboratory discovery to commercial product,” said Nathan Neale, a research scientist at the National Renewable Energy Laboratory. Neale is part of a team working on a similar technology that uses perovskite to create solar powergenerating windows.