Improved glass technology that can dim in sunlight and generate energy
Scientists from the U.S. National Renewable Energy Laboratory (NREL) have reported on the development of a next-generation thermochromic window.
The technology lets the glass change color when exposed to sunlight, reducing excess heat in the room while at the same time converting solar energy into electricity.
This is achieved through a thin film of perovskite sandwiched between two layers of glass, along with an injected vapor. The vapor triggers a reaction in which the perovskite changes its structure and shifts the color of the glass from pale yellow to brown.
As the temperature rises, the process reverses and the glass becomes transparent again. The transition takes about 7 seconds.
The first experimental sample was presented back in 2017; at that point the color change took 3 minutes, required a higher temperature of 65-80℃ (the technology now works at 35-46℃), and offered a narrower range of color gradations.
Despite the reported progress in the research, it remains unclear how many times a thermochromic window can change its color and return to a transparent state, and whether its energy-conversion efficiency declines in the process.
