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In a dye-sensitized solar cell, dye-coated semiconductor nanoparticles are sandwiched, along with the electrolyte, between two glass plates. The dye molecules absorb light and generate electrons, which are transferred to the semiconductor and on to the external circuit. Meanwhile, positively charged holes go to the electrolyte. The big problem with organic dyes in the past has been the difficulty of keeping the charges separated: they tend to recombine and lower currents.
The dye molecule that Wang and his colleagues designed increases the cell's efficiency in three ways: it quickly shuttles electrons to the semiconductor particles; it keeps the electrons and holes from recombining; and it covers a broader spectrum of light, absorbing more red light than was possible before.
At least two companies are commercializing dye-sensitized solar cells. These devices are up to 11 percent efficient and use ruthenium dyes and a volatile electrolyte. In October 2008, Dyesol opened a factory in Queanbeyan, Australia, to make tiles that can be integrated into building facades. G24 Innovations, in Cardiff, U.K., is making solar chargers for mobile phones.
Wang says that his new work, published online in the journal Chemical Communications, could make the technology cheaper and open up broader applications. "At the moment, the use of toxic and volatile solvents in high-efficiency cells is a big hurdle for the large-scale application of dye-sensitized solar cells," he says.
The researchers are working to boost efficiency even more. Wang says that will involve "mainly extending the spectral response of sensitizers to the infrared and the design of better solvent-free electrolytes."
Meanwhile, Grätzel and his colleagues at Lausanne have set themselves a lofty goal. They plan to reach efficiencies of 14 percent by the end of next year using nonvolatile electrolytes. As for the dye, either ruthenium-based dyes or organic dyes could win the race, he says. And he is optimistic about cheaper organic dyes. "If you see how efficiencies of both have gone up, the slope is steeper for organic molecules," Grätzel says. "If you extrapolate, it could be a year or so before they overtake."
Improved dyes and electrolytes could make the Grätzel solar-cell design more practical.
With catalysts created by an MIT chemist, sunlight can turn water into hydrogen. If the process can scale up, it could make solar power a dominant source of energy.
The holy grail, for the economic winner(s).
How much does it cost?
Scaled to the global level.
In ¢/kWh and $/kW, over the long run.
Too much emphasis is put on efficiency and not enough on total cost. Does it matter to me if 20% of my garage and house are covered with solar cells or 80%? No! All I care about is $/kWh over the cell's lifetime. Can solar compete with my coal fired local utility?
When the the numbers match my next re-roofing will include solar.
Using the Visible Spectra and Applications in Space
Currently, I guess most of the solar cells (including Dye-sensitized ones) convert primarily the IR region of the spectrum. Much higher efficiencies can be achieved if all the frequencies of radiation reaching the Earth's surface are captured and converted.. the trick is to do it simultaneously for all the frequencies.
I do not see these dye-sensitized cells in space anytime soon.. the dye molecules are likely to be ionised due to Uv and other high energy radiation,so the much more expensive but more efficient Germanium based cells are preferred for now. But this is undoubtedly a breakthrough for civilian based applications.
This looks like a good place to make Hydrogen out of water. Nanotechnology could strip the hydrogen molecule off for fuel.
Manufacturing in the United States is in trouble. That's bad news not just for the country's economy but for the future of innovation.
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asogan
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UV Stability
My gut feel is that both dyes will be necessary for roll out.
The organic dye is generally UV sensitive, so applications will typically be for indoor use e.g. To power the standby modes for electronic goods.
The ruthenium dye is more robust and suitable for outdoor use.
To those who don't know, the DSSC can absorb light across a very wide spectrum, so yes, it CAN be used indoors and will absorb light even in cloudy weather.
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