Researchers receive $2.4 million ARPA-E grant to improve solar cell efficiency

January 2, 2013 by Bob Yirka, weblog
solar cells

(—Researchers at the California Institute of Technology have received a $2.4 million grant from the U.S. Advanced Research Projects Agency for Energy (ARPA-E) to study the feasibility of using a new technique to capture more energy from sunlight. The grant is based on work described by Caltech's Harry Atwater and Albert Polman in a paper they've had published in the journal Nature Materials.

Most solar panels in use today follow a sandwich approach where layers of photovoltaic semiconductors are stacked – each is designed to get the most energy from a specific . The problem with this approach is that the layer with the lowest current limits the amount of electricity that can be generated. Because of this, efficiency levels for current is below 20 percent. To get around this problem, Atwater and colleagues suggest an alternative approach that allows for separating as many as eight to ten of the colors in the and directing each to a solar cell designed for that particular wavelength.

The researchers suggest that technology involved in separating and directing different has evolved to the point where it should now be feasible to create solar cells that not only are much more efficient – over 50 percent – but are every bit as inexpensive as those being sold today. As one example they note the progress that has been made with , which work by directing different wavelengths of light in very small (pixel sized) devices.

They suggest that by using precisely structured materials to sort sunlight into several different wavelengths, it should be possible to direct each to a semiconductor that has been tuned to be the most efficient for that wavelength. The end result should be the absorption of more energy overall, allowing for the generation of more electricity (and less heat) from the same amount of sunlight.

Their idea isn't completely new of course, many research centers have created solar cells using very similar ideas. What's new is the idea that advances in nanomaterials should allow for such cells to be mass produced in a way makes them cost effective – and that is what the team plans to use the grant money to discover.

Explore further: Researchers create new nanostructure that absorbs broad spectrum of light from all angles

More information: Reference: Nature Materials 11, 174–177 (2012) doi:10.1038/nmat3263

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1 / 5 (3) Jan 02, 2013
Is this article a joke written by a monkey? . Multijunction solar cells are described in simple terms above. Heyve existed fro 10 years and are pricey. Whatever the award is for.....was not adequately described above
5 / 5 (1) Jan 02, 2013
@Jeddy-- The article is awkwardly written but the last paragraph clarifies the project: Multijunction cells are not new and they are currently expensive -- The purpose of the grant is to try to produce these cells more cheaply with nanotechnology.
This research is potentially game-changing, and I hope we will get some updates as the project progresses.
2.5 / 5 (4) Jan 02, 2013
You always hear about "game changing" technology with solar power.

I'm at the point now where I don't want to hear about it...just show me.
not rated yet Jan 02, 2013
@Jeddy - This is grant is NOT for the current stacked multi-junction cells where each layer in the stack absorbs a different wavelength range.

This grant is for splitting the light into its spectral components (e.g., with a prism, diffraction grating, or wave-length-selective mirrors), and having a separate cell (similar to a single layer of a multijunction cell) for each color of the resulting 'rainbow'.
The advantage over multi-junction cells is that the layers do not need to be current-matched (although this would still be helpful) or lattice-matched (or have the complex grading layers that eliminate the needs for lattice-matching).
The disadvantage is more complex optics, and probably a larger area to cool (although with less heat per area).

@Modernmystic - I agree - the press annoyingly writes up every research advance as if it were the one sure road to saving the world rather than one out of hundreds of long-shot possibilities.
not rated yet Jan 03, 2013
How the subsidization of solar programs usually ends The government has committed nearly $40 billion to clean energy projects. The first loan guarantee went to Solyndra Inc., a California solar firm backed by an Obama fundraisers. But instead of picking a winner, the government backed a loser. The firm failed, putting more than 1,000 people out of work and taxpayers on the hook for $535 million. Among questions now: Did the White House unduly influence the process? Did the Energy Department rush its first commitment, ignoring warning signs about the company's viability? With compare to it, the replication of cold fusion findings is still maintained with volunteers as a garage science. It's not surprising, because it threats just the well subsidized job positions in battery and solar industry research.
1 / 5 (1) Jan 03, 2013

Don't forget the reason why the government invests instead of private industry is because they are inherently high risk projects. Too risky for private industry to invest in but necessary for advancement toward the ultimate goal of feasibility. The actual problem is that we don't fund these companies enough to get through the problems that make it unfeasible to the point where they become profitable enterprises with a return on the investment.

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