Cheap "Popcorn Ball" Solar Cells Set Efficiency Record
April 13, 2008 2:00 PM
comment(s) - last by
A close up of a single ball, 300 nm across. The ball is made up of 15 nm grains.
(Source: University of Washington)
Millions of the balls compose a layer of the solar cell.
(Source: University of Washington)
The thin light-absorbing zinc oxide surface, pictured here in a picture from a scanning electron microscope, is about 10 um thick, and composed of the popcorn ball like structures.
(Source: University of Washington)
While not very tasty, these balls are extra efficient
With gas prices going up, refining capacity stretched to its max, and the reality that fossil fuels will eventually be depleted settling in, interest in alternative energy solutions of various types is at an all time high. Among these is
renewed vigor in the solar power industry
building massive new plants
new ground breaking research
, the rather old field of solar power, is adapting quickly to the latest tech.
The University of Washington just made another breakthrough in solar power, that while humorous sounding, certainly offers serious gains. Researchers at the university studying solar cell configurations discovered that by implementing a popcorn ball design -- tiny spheres clumped into bigger porous spheres -- efficiency in cheap solar cells was near doubled.
The dramatic improvement was included in findings presented at the national meeting of the American Chemical Society in New Orleans. Lead author Guozhong Cao, a UW professor of materials science and engineering, states, "
We think this can lead to a significant breakthrough in dye-sensitized solar cells."
Dye-sensitive cells have been in vogue since early pioneering research in 1991. The cells have the advantage of being
flexible, cheaper, and easier to manufacture
than brittle silicon solar cells. Rough surfaces have been a focus in the dye-sensitive field's research, with researchers reach efficiencies of approximately 10 percent capture of the suns energy absorbed. This efficiency is only about half that of traditional silicon solar cells found on roof tops and calculators but with the lower price its is enough to stay competitive with the silicon cells.
The University of Washington researchers looked to compare homogeneous rough surfaces with various clumped designs, instead of trying to maximize the efficiency of the well researched homogeneous rough surface. One dilemma that researchers faced was the size of the grains used. Bigger grains, closer to the visible wave length of light cause the light to bounce around inside the thin-light absorbing surface, increasing the probability that it will be absorbed. On the other hand, small grains have a bigger surface area per volume, increasing absorbtion.
Explains Cao, "You want to have a larger surface area by making the grains smaller. But if you let the light bounce back and forth several times, then you have more chances of capturing the energy."
Other researchers have tried unsuccessfully to improve efficiency by mixing small and large grains. The UW researchers instead took tiny 15 nm grains and clumped them together into 300 nm agglomerations, essentially making large grains composed of small grains, an approach that resembles macroscopic scale popcorn balls.
Each gram of the material has an incredible surface area of 1,000 square feet per gram covered in light absorbing pigment. Thanks to the complex design light also gets trapped inside the larger balls, increasing absorption remarkably. The researchers were surprised at their success, saying it surpassed even their best hopes. Says Cao, "We did not expect the doubling. It was a happy surprise."
The overall efficiency was 2.4 percent for small grains only, the current highest efficiency achieved for the material (there are higher efficiency materials, hence the 10 percent in commercial designs). The popcorn-ball design showed an overall efficiency of 6.2 percent, a 258 percent increase in efficiency. Cao states, "The most significant finding is the amount of increase using this unique approach."
The research used the pigment zinc oxide, which is of lower efficiency than the commercially used titanium oxide, but easier to work with during experiments. Titanium oxide layers are expected to show similar gains. Cao gives an update on this explaining, "We first wanted to prove the concept in an easier material. Now we are working on transferring this concept to titanium oxide."
While titanium oxide cells currently have a record efficiency of 11 percent, the researchers hope that by using the new method they can by far surpass this old record, possibly even surpassing silicon cell efficiencies. Such progress could make
silicon cells, used for decades
, obsolete, replaced by cheaper, more efficient, flexible cells.
The research was funded by the National Science Foundation, the Department of Energy,
and the Air Force Office of Scientific Research. The postdoctoral research was co-authored by Qifeng Zhang, research associate Tammy Chou and graduate student Bryan Russo all in the UW material sciences department, and Samson Jenekhe, a UW professor of chemical engineering.
This article is over a month old, voting and posting comments is disabled
Solid silicon isn't quite dead yet
4/13/2008 6:39:25 PM
An Australian method of creating cells is only a few years away from commercial production. The ANU developed 'sliver' cells, where basically they create a normal solid silicon chip, and then etch away lines to create a connected series of tiny (nanometer order) slivers of silicon.
I'll try and find a link, but basically it significantly increases surface area (rays that fall between slivers reflect back and forth between walls and get further absorbed), greatly reduces the amount of silicon required (reducing costs and resource consumption) and makes the cells flexible so it can be mounted in clothes etc.
Unfortunately, no-one is Aus could stump the cash to put it into large scale production, so it's going stateside to be funded and built :(. But as long as it makes it into production and helps, I'm happy. Although it would be nice if people knew who came up with it.
"If you can find a PS3 anywhere in North America that's been on shelves for more than five minutes, I'll give you 1,200 bucks for it." -- SCEA President Jack Tretton
Cheap Alternative Energy Now Just a Print Job Away
March 7, 2008, 11:44 AM
Massive 280 MW Solar Plant Coming to Arizona in 2011
February 28, 2008, 10:45 AM
New Material Promises to Save LCD, Solar Power Industry
December 29, 2007, 1:13 PM
New "Solar" Nanowires: Cheap and Durable
October 25, 2007, 2:50 PM
Sharp Readying Thin Solar Cell Output For 2008
November 4, 2007, 10:58 AM
Microsoft Co-founder Paul Allen Donates $100M to Fight Raging Ebola Epidemic
October 23, 2014, 6:05 PM
Cool Science Video of the Day: Carnivorous Leech Eats Giant Jungle Worm
October 16, 2014, 6:44 PM
Facebook CEO and Founder, Mark Zuckerberg, Donates $25M to Fight Ebola
October 14, 2014, 5:06 PM
Chagrined Over Leaks, CDC Confirms First U.S. Ebola Diagnosis in Dallas, Texas
September 30, 2014, 5:55 PM
Nail Polish May Soon be Able to Detect Date Rape Drugs
August 26, 2014, 7:57 AM
SpaceX Falcon 9-R Rocket Suffers Malfunction, Self-Destructs During Test Flight
August 23, 2014, 9:36 AM
Most Popular Articles
Amid Theater Boycott Netflix Defiantly Plans New Movies, Plus 3 TV Shows for 2015
October 24, 2014, 7:30 PM
AT&T Defeats Purpose of New Apple SIM, Locks iPad Air 2 SIMs to Its Network
October 24, 2014, 2:17 PM
CVS, Rite Aid Kill Unofficial Apple Pay Support, Burn Google Wallet Users in the Process
October 25, 2014, 5:26 PM
1 Million Credit Card Activated on Apple Pay Within 72 Hours, Walmart CEO Hopes Visa "Suffers"
October 28, 2014, 8:17 AM
Microsoft's Figures Show Desktop Users Flocking to Windows 10 Preview
October 27, 2014, 11:04 AM
Latest Blog Posts
Costco Gives Employees Thanksgiving Off; Wal-Mart Leads "Black Thursday" Charge
Oct 29, 2014, 9:57 PM
"Bear Selfies" Fad Could Turn Deadly, Warn Nevada Wildlife Officials
Oct 28, 2014, 12:00 PM
The Surface Mini That Was Never Released Gets "Hands On" Treatment
Sep 26, 2014, 8:22 AM
ISIS Imposes Ban on Teaching Evolution in Iraq
Sep 17, 2014, 5:22 PM
Space Terrorism is a Looming Threat For the United States
Apr 23, 2014, 7:47 PM
More Blog Posts
Copyright 2014 DailyTech LLC. -
Terms, Conditions & Privacy Information