A novel, transparent, two-layer solar film — possessing an impressive solar conversion efficiency of 7.3% — has been created by researchers at the University of California–Los Angeles. The solar film can be placed on windows, buildings, sunroofs, electronics displays, etc; harvesting energy while still at the same time allowing light to pass through and visibility/transparency to be maintained.
The new solar film is essentially an improved form of the “breakthrough photovoltaic cell design” that the same researchers unveiled last year — an improved form with double the efficiency, that is. It consists of two thin polymer solar cells that work together to maximize sunlight collection and conversion to electricity — the two cells absorb more light than single-layer solar devices do because together they absorb light from a wider part of the solar spectrum. There’s also a thin layer of ‘novel materials’ present between the two cells that works to reduce energy loss.
The University of California–Los Angeles has more:
The tandem polymer solar cells are made of a photoactive plastic. A single-cell device absorbs only about 40% of the infrared light that passes through. The tandem device — which includes a cell composed of a new infrared-sensitive polymer developed by UCLA researchers — absorbs up to 80% of infrared light plus a small amount of visible light.
While a tandem-structure transparent organic photovoltaic (TOPV) device developed at UCLA in 2012 converts about 4% of the energy it receives from the sun into electric power, the new tandem device — which uses a combination of transparent and semi-transparent cells — achieves a conversion rate of 7.3%.
Researchers say that the new cells could serve as a power-generating layer on windows and smartphone displays without compromising users’ ability to see through the surface. The cells can be produced so that they appear light gray, green or brown, and so can blend with the color and design features of buildings and surfaces.
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“Using two solar cells with the new interfacial materials in between produces close to two times the energy we originally observed,” stated Yang Yang, the Carol and Lawrence E. Tannas, Jr, Professor of Engineering at the UCLA Henry Samueli School of Engineering and Applied Science. “We anticipate this device will offer new directions for solar cells, including the creation of solar windows on homes and office buildings.”
The researchers also note that, thanks to the fact that the materials involved can be processed at low temperatures, they are relatively easy to manufacture, as compared to most other solar cell designs. A fact that should help to keep the cost of producing them relatively low.
It all sounds pretty good. This sort of solar cell sounds like a good fit for dense urban areas, where economy of space is an important factor in decisions concerning solar energy. And as we’ve reported before, solar-skinned buildings are becoming increasingly common and should continue to do so well into the future — leaving lots of room for new transparent solar cell designs.
The new research was funded primarily by the Air Force Office of Scientific Research, the Office of Naval Research, and EFL Tech. The new research was published online July 26th in the Royal Society of Chemistry journal Energy & Environmental Science.