In the face of a string of intensely demoralizing federally backed alternative energy projects with Solyndra taking over a half billion dollars alone – solar panels seem to lead the way into a dead end. Except that China’s solar industry is very much alive and competitive.
The technology advances usually start in the U.S. But the U.S. and even more so in the European Union, the photovoltaic industry is in hard times. Federal shenanigans aside – photovoltaic solar electrical energy production costs too much.
A UCLA team is describing a new kind of polymer solar cell (PSC) that produces energy by absorbing mainly infrared light, not visible light, in a study paper published in the ACS journal Nano. The cells are better than 66% transparent to the human eye.
The important news is the team made the device from a photoactive plastic that converts infrared light into an electrical current. This is different than high tech attempts to catch as much spectrum as possible.
Yang Yang, a UCLA professor of materials science and engineering, who also is director of the Nano Renewable Energy Center at California NanoSystems Institute said, “Our new PSCs are made from plastic-like materials and are lightweight and flexible. More importantly, they can be produced in high volume at low cost.”
Low cost matters, a lot.
The new polymer solar cell is quite transparent, an advance toward giving windows in homes and other buildings the ability to generate electricity while still allowing people to see outside.
Yang continues, “These results open the potential for visibly transparent polymer solar cells as add-on components of portable electronics, smart windows and building-integrated photovoltaics and in other applications.”
Polymer solar cells have stimulated research due to their advantages over competing solar cell technologies. Scientists have also been intensely investigating PSCs for their potential in making unique advances for broader applications. Several such applications would be enabled by high-performance visibly transparent photovoltaic (PV) devices, including building-integrated photovoltaics and integrated PV chargers for portable electronics.
So far many attempts have been made toward demonstrating visibly transparent or semitransparent PSCs. However, the demonstrations often result in low visible light transparency and/or low device efficiency because suitable polymeric PV materials and efficient transparent conductors were not well deployed in device design and fabrication.
The UCLA researchers have demonstrated high-performance, solution-processed, visibly transparent polymer solar cells through the incorporation of a near-infrared light-sensitive polymer and using silver nanowire composite films as the top transparent electrode. The near-infrared photoactive polymer absorbs more near-infrared light but is less sensitive to visible light, balancing solar cell performance and transparency in the visible wavelength region.
Another breakthrough is the transparent conductor made of a mixture of silver nanowire and titanium dioxide nanoparticles, which is able to replace the opaque metal electrode used in the past. This composite electrode also allows the solar cells to be fabricated economically by solution processing. With this combination, with a 4% power-conversion efficiency for solution-processed and visibly transparent polymer solar cells has been achieved.
It’s a long way from 15% efficiency, but that cost issue has leading efficiency technology simply – financially out of reach.
The headline is an over statement, a few photovoltaic folks are going great; some are doing fine, others getting by. The news in the major media has been devastating, and the economy in the U.S. with all the government incentives hasn’t lit any kind of fire into the business. Still, the UCLA team is on to something with using the infrared a prime source of thermal energy that’s there for the taking. Cheap enough the market is huge.
There’s a lot missing from the press release and the study paper abstract. Environmental conditions, voltage, ancillary equipment needed and all the rest. If the technology is spared converting from DC to AC current, the team could get some running room.
Photovoltaic has vast market of many low current uses available now and more coming. Running a home or business, charging electric vehicles, and supporting the grid in meaningful amounts isn’t looking practical yet. So far photovoltaic distributed generation is vastly financially impractical.
As more products that self charge become available some are going to use this technology. Momentum will build and photovoltaic will grow.
Meanwhile, how important is that transparency anyway?