Researchers developed a new type of smart window that controls different factors of varying tint, saving up to 40 percent on an average building’s energy costs. These smart windows require power for operation, they complicated to install in existing buildings. This system features solar cells that selectively absorb near-ultraviolet (near-UV) light, so new windows completely self-powered.
Loo, from Princeton university, said, this new technology is actually smart management of the entire spectrum of sunlight, because near-UV light is invisible to the human eye. The researchers set out to harness it for the electrical energy needed to activate the tinting technology.
Using near-UV light to power these windows means that the solar cells can be transparent and occupy the same footprint of the window without competing for the same spectral range or imposing aesthetic and design constraints. Typical solar cells made of silicon black because they absorb all visible light and some infrared heat.
The researchers used organic semiconductors contorted hexabenzocoronene (cHBC) derivatives for constructing new solar cells, because its chemical structure could modify to absorb a narrow range of wavelengths.
To make new solar cells, the semiconductor molecules deposited as thin films on glass, enabling cHBC semiconductors to produce electricity when hits sunlight.
The researchers also created a smart window using electrochromic polymers to control the tint. They can operate solely using power produced by the solar cell. The window changes from clear to dark blue when the near-UV light generates an electrical charge in the solar cell.
The charge triggers a reaction in the electrochromic window, causing it to change from clear to dark blue. When darkened, the window can block more than 80 percent of light.
The research team is also looking to create a flexible version of solar-powered smart window system. That can apply to existing windows via lamination.
They explained that the near-UV solar cell technology can also power internet-of-things sensors and other low-power consumer products.
“It does not generate enough power for a car, but it can provide auxiliary power for smaller devices, for example, a fan to cool the car while it’s parked in the hot sun,” Loo said.
More information: [nature energy]