A team of UCLA researchers has achieved a breakthrough in polymer solar cell (PSC) technology by doubling the efficiency of the transparent solar cells they unveiled last year. Led by Yang Yang, Director of the Nano Renewable Energy Center of California Nano Systems Institute, the team has been developing solar cells made from PSC – a photoactive plastic that converts infrared light into an electrical current. It’s nearly 70% transparent because it produces energy by absorbing mainly infrared light. The new PSC could be applied as film on windows and cell phone displays without compromising the user’s ability to see through the surface.
The PSC is composed of two thin polymer solar cells, one that is transparent and one that is semi-transparent. It now boasts a conversion rate of 7.3%——twice as efficient as—previous devices, researchers say, because the two cells absorb more light than single-layer solar devices as it can use light from a larger portion of the solar spectrum. A single-cell device absorbs only about 40% of the infrared light that passes through, while this double-layer device, which includes a sensitive polymer developed by UCLA researchers, absorbs up to 80% of infrared light plus a small amount of visible light, hence the higher efficiency.
The materials that go into the new PSC are processed at low temperatures, making them relatively easy and inexpensive to manufacture. The cells can be made so that they appear light gray, green or brown to blend in with the surface they are applied on. The transparent solar cells could be used to power buildings by being applied to windows and could also be used to charge electronics as a film on the user interface.