Engineers have suggested a colorful solution to next-generation energy collection: Luminescent solar concentrators (LSCs) in windows. The team designed and built foot-square “windows” that sandwich a conjugated polymer between two clear acrylic panels. The thin middle layer is designed to absorb light in a specific wavelength and guide it to panel edges lined with solar cells. Conjugated polymers are chemical compounds that can be tuned with specific chemical or physical properties for a variety of applications such as conductive films or sensors for biomedical devices.
The polymer compound is poly[naphthalene-alt-vinylene] (PNV) that absorbs and emits red light; however, adjusting the molecular ingredients should make it able to absorb light in a variety of colors. As a waveguide, it accepts light from any direction but restricts how it leaves, concentrating it onto the solar cells that convert it to electricity.
Currently, solar rooftops are the mainstream solution but they need to be oriented toward the Sun to maximize their efficiency. The new solution enables colorful, transparent, or translucent solar collectors to be applied to the outside of buildings.
The amount of juice generated by the test units is far less than that collected by even average commercial solar cells, which routinely convert about 20% of sunlight into electricity.
But the LSC windows never stop working, recycling light from inside the building into electricity when the Sun goes down. Tests show they are more efficient at converting ambient light from LEDs than they were from direct sunlight, even though the sunlight was 100 times stronger.
The team also simulated the return of energy from panels as large as 120" square. They reported these panels would provide somewhat less energy but would still contribute to a household’s needs. The polymer might also be tuned to convert energy from infrared and ultraviolet light, allowing those panels to remain transparent.