Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have reported a breakthrough in the development of a next-generation thermochromic window that not only reduces the need for air conditioning but simultaneously generates electricity.

NREL researcher Lance Wheeler holds a perovskite window prototype that can switch between a variety of colors. Photo by Dennis Schroeder, NREL, taken from globenewswire

The technology, dubbed “thermochromic photovoltaic,” allows the window to change color to block glare and reduce unwanted solar heating when the glass gets warm on a sunny day. This color change also leads to the formation of a functioning solar cell that generates on-board power. Thermochromic photovoltaic windows can help buildings turn into energy generators, increasing their contribution to the broader energy grid’s needs. The newest breakthrough now enables various colors and a broader range of temperatures that drive the color switch. This increases design flexibility for improving energy efficiency as well as control over building aesthetics that is highly desirable for both architects and end users.

A team of researchers at the Ulsan Institute of Science and Technology (UNIST) and Korea University, led by Professors Myung-Hoon Song, Sang-Gyu Kwak and Han-Young Woo, recently announced the development of a PeLED - a perovskite-based LED device, that emits blue light.

The team explained that the perovskite light emitting device, which uses perovskite as a color material, is more than three times more efficient than before and has a high color purity, enabling a clear blue color.

Researchers at Monash University, University of Sydney and University of Melbourne in Australia have addressed a fundamental challenge standing before massive commercialization of perovskite solar cells - light-induced phase segregation, in which illumination, such as sunlight, disrupts the carefully arranged composition of elements within mixed-halide perovskites.

Light-induced segregation often leads to instability in the material’s bandgap, interfering with the wavelengths of light absorbed, while reducing charge-carrier conduction and the efficiency of devices.