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$SIRC Revenues soaring
RGSE 1.50$ BOTTOM BOUNCE SOLAR CALL >>>>>>>>>
Promising Solar Power Technologies
Sunday, June 29, 2008
New cost effective solar energy products are on the near horizon. Let's take a look at some of the promising ones.
MIT reports prototype solar dish passes first tests.
A team led by MIT students this week successfully tested a prototype of what may be the most cost-efficient solar power system in the world--one team members believe has the potential to revolutionize global energy production.
The system consists of a 12-foot-wide mirrored dish that team members have spent the last several weeks assembling. The dish, made from a lightweight frame of thin, inexpensive aluminum tubing and strips of mirror, concentrates sunlight by a factor of 1,000--creating heat so intense it could melt a bar of steel.
MIT Sloan School of Management lecturer David Pelly, in whose class this project first took shape last fall, says that, "I've looked for years at a variety of solar approaches, and this is the cheapest I've seen. And the key thing in scaling it globally is that all of the materials are inexpensive and accessible anywhere in the world."
Pelly adds that "I've looked all over for solar technology that could scale without subsidies. Almost nothing I've looked at has that potential. This does."
Raw Solar
The website Raw-Solar has this diagram explaining the practical application.
A solar thermal dish reflects the rays of the sun onto a small receiver using specially curved mirrors, concentrating the sunlight 1000 times. The high concentration increases the efficiency of the energy collection by reducing the surface area for thermal losses. A robust tracking system keeps the dish pointed directly at the sun all day, maximizing the available sunlight.
Water is pumped through the receiver where the high intensity sunlight heats it to 212-750F (100-400C), making steam. The steam can then be piped into an existing steam system, such as a district energy system or food processing plant.
What makes this system special vs. its competition is that it can use small flat flexible mirrors that can bend in exactly the right shape to concentrate the reflected sunlight on a precise spot. The materials are all easily produced and the team could put this dish together by hand.
Inquiring minds will want to consider this MIT video demonstration of their solar power dish.
http://techtv.mit.edu/file/1076/?skin=popup&file_type=flv
Following is a photographic clip from the demonstration. In the clip below a wooden beam was held where the rays were being concentrated and it immediately caught fire.
http://www.raw-solar.com/img/media/zenphoto/rawsolar-thermal-dish/6.jpg.php
Hot Thin Roofs
Let's now turn our attention to Hot Thin Roofs.
A new solar energy product, thin enough to be built into shingles, may finally make the technology competitive.
With energy prices soaring, affordable solar power would be welcomed by any entrepreneur looking to trim the electric bill. Trouble is, power generated by the most widely available technology - panels covered with photovoltaic (PV) systems, which translate sunlight into AC current - still costs two to three times more than electricity generated from coal and other fossil fuels. That may be about to change.
Several startups, including HelioVolt in Austin, Miasolé in Santa Clara, Calif., and Nanosolar in Palo Alto, are working on a new technology called flexible thin film that's on the brink of making solar more competitive. Nanosolar has just begun to ship its thin-film solar systems to a German utility.
Made from pliant sheets of foil, the solar panels can be molded onto roof shingles, which are at once more attractive than clunky, heavy glass panels and less expensive to produce. In fact, the cost of making thin film is so much lower than traditional solar panels that experts say it could produce electricity for about the national average of 10.4 cents a kilowatt hour.
http://globaleconomicanalysis.blogspot.com/2008/06/promising-solar-power-technologies.html
invest at your own risk, based on your own due diligence, at your own risk tolerance
SOLAR = $$$$$
A very hot sector for this fine summer season .... green is in ...green is global
(record oil today too, I might add)
so....
Let the SUN SHINE .... Good Luck Friend(s)
JT
and a few others to consider ....
and a "new" solar ETF ... KWT
Solar Stocks: Nine That Will Shine in a Bull Market
by: Rick Shea
posted on: April 21, 2008
As the market rebounds, investors continue to reward the large cap growth leaders, and alternative energy led by solar has been one of the prime beneficiaries. The need for alternative energy continues to be a main focus for all governments as oil continues it's climb to over $110 a barrel. Solar stocks are getting the most headlines because they are farther along the commercialization continuum and they are more prevalent than their wind and alternative fuel counterparts.
Any discussion about solar companies must start with First Solar (FSLR). Clearly, the leader in the sector according to Wall Street based on its thin film technology, First Solar's stock price has resumed its climb to near record levels as investors await its Q1 earnings report.
Suntech (STP) and SunPower (SPWR) are the next two leading players based on market cap, but they primarily use silicon-based technology for their products. SunPower just released strong first quarter 2008 numbers but some analysts had some concerns about slowing sales growth for the next quarter based on a single comment during its conference call.
Additional players include LDK Solar (LDK), Trina Solar (TSL), Evergreen Solar (ESLR) and Canadian Solar (CSIQ).
There are two main questions when investing in solar stocks:
First, which technology (thin film vs. silicon) is likely to offer the best long term business model for cost and efficiency. Again, based on market cap and relative performance the market is betting that customers will prefer thin film technology led by First Solar. While I tend to agree I am certain that the market will be large enough for both technology forms to compete and provide strong sales and profits.
Second, which stocks offer the best values and are likely to maintain the growth rates that investors need to drive higher market capitalizations.
The following chart analyzes the top players with the key growth rates and relative value.
You can see that Wall Street believes that First Solar will prevail based on a market cap that is three times the next largest competitor. You can also see its stock is priced for perfection. First Solar has a history of trouncing estimates and will likely do so again this quarter.
SWPR and STP are the next largest competitors with STP actually showing the largest sales estimate for Q1 2008. Both are well-positioned to lead the silicon based technology and sport reasonable valuations with forward P/E's of 27 and 18 respectively. Their PEG's (price to earnings growth) is actually very attractive and lower than most slower growing companies.
Both Canadian Solar (CSIQ) a Chinese company and LDK are interesting plays. Both are showing strong growth with below average valuations. LDK's PEG is ridiculously low vs. the other solar companies and vs. the overall market. So what's this all mean for the average investor looking to buy alternative energy and solar stocks. I believe FSLR will deliver on Q1 earnings and lead the group to new highs.
I will continue to maintain my long positions in FSLR, SPWR and STP until their valuations get too high. At that point it may be worthwhile to switch into some of the smaller names particularly LDK and CSIQ. The leaders will lead the sector up until valuations get out of hand and then others will play catch up shortly after.
FYI: I also like Cree Inc. (CREE) and Zoltek Companies Inc. (ZOLT) as additional long-term plays in the alternative energy sector.
Disclosure: The author is long FSLR, STP & SPWR.
http://seekingalpha.com/article/73087-solar-stocks-nine-that-will-shine-in-a-bull-market
ReneSola Ltd. (SOL)
website http://www.renesola.com/
ReneSola, Ltd., through its subsidiaries, engages in the manufacture and sale of solar wafers and related products in the People's Republic of China. It offers feedstock, ingots, and wafers for the solar industry. The company sells solar wafers to Chinese and international PV cell manufacturers. ReneSola was founded in 2005. It was formerly known as ReneSol, Ltd. and changed its name to Renesola, Ltd. in April 2006. Further, the company changed its name to ReneSola, Ltd. in June 2006. ReneSola is based in Jiashan, China.
Share Statistics
Average Volume (3 month)3: 1,238,560
Average Volume (10 day)3: 1,445,670
Shares Outstanding5: 100.00M
Float: N/A
% Held by Insiders1: N/A
% Held by Institutions1: 0.80%
Shares Short (as of 26-Mar-08)3: 1.05M
Short Ratio (as of 26-Mar-08)3: 1.8
Short % of Float (as of 26-Mar-08)3: N/A
Shares Short (prior month)3: 770.57K
Holographic Solar
A novel approach to concentrating sunlight could cut solar panel costs.
By Prachi Patel-Predd
Rows of silicon solar cells alternate with rows of transparent holograms in Prism Solar's concentrators. (Courtesy of Prism Solar)
The main limitation of solar power right now is cost, because the crystalline silicon used to make most solar photovoltaic (PV) cells is very expensive. One approach to overcoming this cost factor is to concentrate light from the sun using mirrors or lenses, thereby reducing the total area of silicon needed to produce a given amount of electricity. But traditional light concentrators are bulky and unattractive -- less than ideal for use on suburban rooftops.
Now Prism Solar Technologies of Stone Ridge, NY, has developed a proof-of-concept solar module that uses holograms to concentrate light, possibly cutting the cost of solar modules by as much as 75 percent, making them competitive with electricity generated from fossil fuels.
The new technology replaces unsightly concentrators with sleek flat panels laminated with holograms. The panels, says Rick Lewandowski, the company's president and CEO, are a "more elegant solution" to traditional concentrators, and can be installed on rooftops -- or even incorporated into windows and glass doors.
The system needs 25 to 85 percent less silicon than a crystalline silicon panel of comparable wattage, Lewandowski says, because the photovoltaic material need not cover the entire surface of a solar panel. Instead, the PV material is arranged in several rows. A layer of holograms -- laser-created patterns that diffract light -- directs light into a layer of glass where it continues to reflect off the inside surface of the glass until it finds its way to one of the strips of PV silicon. Reducing the PV material needed could bring down costs from about $4 per watt to $1.50 for crystalline silicon panels, he says.
The company is expecting to pull in another $6 million from interested venture capitalists and start manufacturing its first-generation modules by the end of the year, selling them at about $2.40 per watt. Next-generation modules with more advanced technology should bring down the cost further.
In their ability to concentrate light, holograms are not as powerful as conventional concentrators. They can multiply the amount of light falling on the cells only by as much as a factor of 10, whereas lens-based systems can increase light by a factor of 100, and some even up to 1,000.
But traditional concentrators are complicated. Since the lenses or mirrors that focus light need to face the sun directly, they have to mechanically track the sun. They also heat up the solar cells, and so require a cooling system. As a result, although they redirect light with more intensity than the hologram device, "they're unwieldy...and not as practical for residential uses," says National Renewable Energy Laboratory spokesperson George Douglas.
Holograms have advantages that make up for their relatively weak concentration power. They can select certain frequencies and focus them on solar cells that work best at those frequencies, converting the maximum possible light into electricity. They also can be made to direct heat-generating frequencies away from the cells, so the system does not need to be cooled. "In this way, you are efficiently using only that part of the sunlight that really matters," says Selim Shahriar, director of the atomic and photonic technology laboratory at Northwestern University in Evanston, IL.
Also, different holograms in a concentrator module can be designed to focus light from different angles -- so they don't need moving parts to track the sun.
Prism Solar's system incorporates these advantages. Nevertheless, to be competitive with other solar technologies available today, the company might need to reduce its price below $2.40 a watt, says Christo Stojanoff, professor emeritus of engineering at the Aachen University of Technology in Germany.
CEO Lewandowski says the holographic modules will cost about $1.50 per watt in a few years, using their second-generation technology, which will have solar cells sandwiched between two glass panels containing holograms. At that price, they'll start to compete with fossil fuel-generated electricity, which now costs almost three times less than conventional solar electricity, according to San Francisco, CA-based research and consulting company Solarbuzz.
The modules' intensive use of glass could be adding to their cost, says Douglas. Still, such a novel idea for a concentrator, using holograms, could be a lucrative investment because it needs less silicon than flat-panel modules and therefore saves money. The high demand for solar cells in Germany and other European countries "has now outstripped the supply, which has [led to] a silicon shortage and a shortage of manufacturing in the photovoltaic world," he says.
Although the idea of holographic solar concentrators has been around since the early 1980s, no one has developed them commercially yet, according to Professor Stojanoff, who has investigated the technique extensively. His company, Holotec GmbH in Aachen, Germany, researches and manufactures holographic materials. Also, Northeast Photosciences, a Hollis, NH-based company, came close to manufacture, before it went defunct for reasons unrelated to the technology or to finance, he says.
So, if all goes according to plan, Prism Solar could be the first company to manufacture and sell holographic solar concentrator modules.
(To contuinue reading:)
http://www.technologyreview.com/read_article.aspx?ch=biztech&sc=&id=16736&pg=2
THE HOUSE OF THE RISING SUN POWER
Can A Home Solar Energy System Fit Your Budget?
Most homeowners think of solar energy this way: It's something they've heard of, it's something that's good for the environment, and it's something that has about as much bearing on them and their houses as an Alien-Broadcast Rejection System made of aluminum-foil wallpaper. But solar energy is no longer just for hippies, dippies, satellites, and remote vacation properties—it's getting mainstream.
In the last Eco-Logical, we learned about the different types of solar-energy systems and how they work. In today's article, we see how solar might be a good bet for our own houses—and can be affordable.
Household Solar Energy Overview
Solar power is one of the most environmentally benign energy sources available. Just 20 days picture of the sun of sunshine produces the same amount of energy as everything stored in earth's reserves of oil, coal, and natural gas—yet does not come close to producing the same amount of environmental damage as even one of those options.
The solar energy that reaches earth can be captured and utilized in your home. One simple way is to design homes to take advantage of natural lighting during the day—opening or closing blinds and curtains to reject or allow in the sunlight, depending on whether you're in a cooling or heating cycle. Solar-energy systems can also be installed that will collect and store enough energy to heat and cool your home, heat your water, and generate electricity.
Solar Energy Installation in the US and Elsewhere
Solar collectors were very popular in the US in the early 1980s, in the aftermath of the energy crisis. Federal tax credits for residential solar collectors also helped. In 1984, 16 million square feet of collectors were sold in the United States. When fossil fuel prices dropped in the mid-1980s and picture of solar array for generating electricity; CAPTION: A solar array can be placed in your yard or on your roof. President Reagan did away with the tax credit in 1985, demand for solar collectors plummeted. In 1987, sales were down to only 4 million square feet. Most of the more than one million solar collectors sold in the 1980s were used for heating hot tubs and swimming pools.
In other countries, solar collectors are much more common. Israel requires all new homes and apartments to use solar water heating. In Cyprus, over 90 percent of homes have solar water heaters. In the United States, the low cost of natural gas undercuts active solar water and space heaters. But in homes with electric water heaters, solar collectors make sense, saving between $250 and $500 per year.
Is Solar Energy Right for Your House?
Converting a home's electricity to run on solar power has become much more cost-effective than when the technology was first introduced. The cost of solar power has declined nearly 90 percent over the past two decades, and studies suggest that the price will continue to fall. Although the up-front costs of conversion are not insignificant—a typical household system can cost anywhere from $10,000 to $40,000—the energy generated can meet all or part of your future energy needs, lowering your utility bills and helping to pay for the initial cost of the system over time. In fact, homes that generate cartoon of happy sun more power than they need and remain connected to the energy grid may actually put that extra energy into the grid and receive a rebate from the local electric company. (Contact your utility to see if this option is available in your area, or see a map of state programs at the Union of Concerned Scientists' web site.)
Incentive programs also help make solar power more affordable. These programs can include personal-, sales- and property-tax incentives, rebates, grants, loans, and leasing. By taking advantage of these incentives, you could reduce the overall cost of solar power by 50 percent or more. DSIRE—the Database of State Incentives for Renewable Energy—offers a comprehensive listing of state and local programs, as well as incentives offered by specific utilities.
Maybe your previous thoughts about all things solar have naturally leaned towards a plan to slather on some Minus-10 suntan lotion and try to get into the Hamilton Book of Tanning Records for "Most Days in a Row of Being Sun-Dazed." But from an energy perspective, the sun is well worth worshiping.
“RAH” FOR RA!
Types of Solar Power and How They Work
Some people enjoy baking cookies in the oven, some people enjoy baking themselves in the backyard. Even if oil-soaked sun-worshiping Saturday afternoons are the most direct experience most of us every get with the energy of the sun, we know picture of the sun instinctively that the sun is essential for life. It turns out it's also essential for just about any type of energy you can think of.
Solar energy is free and inexhaustible, and has been for the 5 billion years or so that the planet has been in existence. In the broadest sense, solar energy supports all life on earth and is the basis for almost every form of energy we use.
* The sun makes plants grow, which are burned as fuel or rot in swamps and are compressed underground for millions of years to become coal and oil.
* Heat from the sun causes temperature differences between areas, causing the wind to blow.
* Water evaporates because of the sun, falls on high elevations, and rushes down to the sea, spinning turbines as it passes.
But the term "solar energy" usually refers to ways the sun's energy can be used as heat, lighting, and electricity.
One simple, obvious use of sunlight is to light our buildings. The sun can also affect a building's heating and cooling costs: If properly designed, a building can capture the sun's heat in the winter and reject it in the summer, while using daylight year round for lighting. With the exception of that guy down in the bowels of the Grinning Planet accounting department who seems to thrive on flickering fluorescent lighting, most of us prefer natural light.
Solar Energy Collectors/Concentrators
Besides using design features to maximize use of the sun, some buildings have active systems to gather and store solar energy. Solar collectors sit on the rooftops of buildings to collect solar energy for space heating, water heating, and space cooling. Most solar collectors are large flat boxes, painted black on the inside, with glass covers. In the most common design, pipes in the box carry liquids that take the heat from the box and bring it into the building. This heated liquid, usually a water-alcohol mixture to prevent winter freezing, is used to heat water in a tank or is put through radiators to heat the air.
Oddly enough, because of the cooling effect moist air has when it evaporates, solar heat can also drive a cooling system. Such systems are currently at work in humid southeastern climates, like that of Florida.
By using mirrors and lenses to concentrate the rays of the sun, solar thermal systems produce high temperatures that can be used to heat water for producing picture a trough style solar energy system steam to drive an electric turbine or for industrial applications, like boiling water to sterilize soup cans.
Solar concentrators come in three main designs: parabolic troughs, parabolic dishes and central receivers. The most common is parabolic troughs—long, curved mirrors that concentrate sunlight on a liquid inside a tube that runs parallel to the mirror. Parabolic dish concentrators and central receivers can produce much higher temperatures and produce electricity more efficiently but are more complicated and are not in common use.
Solar Energy – Photovoltaics (PV)
In 1839, French scientist Edmund Becquerel discovered that certain materials would give off a spark of electricity when struck with sunlight. Solar cells work because the silicon substrate has a weak grip on its electrons. The cells are made of two layers of silicon, one with too many electrons (the n-layer) and one with too few (the p-layer). When light hits the first layer, electrons are knocked loose. As they flow toward the layer with too few electrons, they pass through an electric circuit, the current from which can be used to power equipment and devices.
In the 1970s, a serious effort began to produce photovoltaic panels that could provide cheaper solar power. Experimenting with new materials and production techniques, solar manufacturers cut costs for solar cells rapidly, as the following graph shows.
Many solar panels are used today to power cellular phone transmitters, road signs, and water pumps, as well as millions of solar watches and calculators. But most of the market for solar electric is concentrated in off-grid homes, in the villages of developing countries and the vacation homes of industrial countries. Developing nations see PV as a way to avoid building long and expensive power lines to remote areas.
Recently, even utilities in developed countries have been attaching photovoltaics to their power grids. In some locations, it is less costly and politically difficult to install distributed solar panels than to upgrade the transmission and distribution system needed to meet ever-growing electricity demand.
This distributed-generation approach provides a new model for the utility systems of the future. Small generators, spread out in a city and controlled cartoon drawing of a solar panel by computers, could replace the large coal and nuclear plants that dominate now.
As the cost of photovoltaic systems continues to decline, they will find increasingly larger niches. No other electrical generator is as easy to install or maintain. Even among the various types of renewable energy, photovoltaics have great potential. The cells are made of silicon, one of the most plentiful materials on earth, and they draw power from the everlasting sun, so they will never run into the problem of fuel scarcity. As PV prices continue to fall, solar power will become a significant source of electricity in the 21st century.
Solar Energy Wrap Up
We now pause to remember our dear departed surfing Uncle Sandy, who once started a referendum in Beach City to annex "the warmth of the sun and all of the gnarly waves." We suspect that all those years of sunlight striking his head must have knocked loose a few cranial electrons.
How Plastic Solar Cells Turn Sunlight Into Electricity
December 13, 2006
Science Daily — A new analytical technique that uses infrared spectroscopy to study light-sensitive organic materials could lead to the development of cheaper, more efficient solar cells. Using infrared (IR) spectroscopy to study the vibrations of atoms within the material, the technique provides information about the movement of electrons within a film of carbon-based materials.
Obtaining this information is a critical step in the development of a new class of solar cells, which promise significant savings in production costs compared to conventional silicon-based cells. The new analytical technique, published as the cover story in this week's issue of the Journal of Physical Chemistry B, was developed by a team led by Penn State University researcher John B. Asbury, assistant professor of chemistry.
Organic photovoltaic devices (OPV) have become important because they are much less expensive to produce than silicon-based solar cells. The material consists of a film made of two different types of chemicals: a polymer that releases an electron when it is struck by a photon of light and a large molecule that accepts the freed electrons, which is based on the soccer-ball-shaped "buckminsterfullerene" carbon molecules popularly known as "buckyballs."
Because the electrical interactions needed to produce an electric current occur at the interfaces of the two components of this polymer blend, materials scientists need to understand the arrangement of molecules in the film. Asbury's new analytical technique provides a closer look at this arrangement than the techniques that traditionally have been used. Previous studies, using atomic-force microscopy, supply general information about the packing of the molecules, but they provide very limited information about the interfaces where the molecules actually come together. IR spectroscopy, on the other hand, provides a more detailed picture of the interface by tracing the exchange of electrons between two molecules of the film.
"The problems with OPVs today are that they are not efficient enough and they tend to stop working over time," says Asbury. In order to develop a useful electric current, the flow between the two components must be optimized. "To improve performance, we need to understand what happens at the molecular level when light is converted to electrons," Asbury explains.
When the film is exposed to light, each photon excites an electron in the polymer. If an interface between the polymer molecule and the functionalized buckminsterfullerene exists, a current can be produced. However, in the materials developed to date, many of the electrons appear to become sidetracked. Asbury exposes the film to light using ultrashort laser pulses, which causes photons of light to be converted to electrons across the entire surface at the same time. Two-dimensional IR spectroscopy is used to monitor the vibration of the molecules within the film. "The vibrations of the molecules are strongly affected by the presence or absence of electrons," says Asbury. "We use these vibrations as a probe to track the movement of electrons. By varying the structures of the materials, we expect to identify the side paths that reduce efficiency and ultimately to use that information to guide material design." The ultimate goal is a solar cell that is sufficiently inexpensive and efficient that it can be used on a rooftop to provide the electrical energy needed in a building.
In addition to Asbury, the Penn State research team includes graduate students Larry W. Barbour and Maureen Hegadorn. The work was funded by the Camille and Henry Dreyfus Foundation, the Petroleum Research Fund, and Penn State.
Note: This story has been adapted from a news release issued by Penn State.
A Boost For Solar Cells With Photon Fusion
October 13, 2006
Science Daily — An innovative process that converts low-energy longwave photons (light particles) into higher-energy shortwave photons has been developed by a team of researchers at the Max Planck Institute for Polymer Research in Mainz and at the Sony Materials Science Laboratory in Stuttgart. With the skillful combination of two light-active substances, the scientists have, for the first time, manipulated normal light, such as sunlight, to combine the energy in photons with particular wavelengths (Physical Review Letters, October 4, 2006). This has previously only been achieved with a similar process using high-energy density laser light. The successful outcome of this process could lay the foundation for a new generation of more efficient solar cells.
The efficiency of solar cells today is limited, among other reasons, by the fact that the longwave, low-energy part of the sunlight cannot be used. A process that increases the low level of energy in the light particles (photons) in the longwave range, shortening their wave length, would make it possible for the solar cells to use those parts of light energy that, up to now, have been lost, resulting in a drastic increase in their efficiency. The equivalent has only been achieved previously with high-energy density laser light which, under certain conditions, combines two low-energy photons into one high-energy photon - a kind of photonic fusion.
This is a significant step forward for the scientists at the Max Planck Institute for Polymer Research and at the Sony Materials Science Laboratory. In developing this process, they have succeeded, for the first time, in pairing up photons from normal light, thus altering the wavelength. They used two substances in solution, platinum octaethyl porphyrin and diphenylan-thracene, which converted the longwave green light from a normal light source into shortwave blue light. Similar to the process in laser light, this also pairs up photons, but in a different way.
When a molecule is manipulated by laser light to take up two photons, which is only probable if it is literally bombarded with a laser beam of photons, the molecules in this case only receive one photon. Two photon partners are brought together between the molecules via a different mechanism called triplet-triplet annihilation. By selecting different, corresponding "matchmaker" molecules, it is possible to combine the energy from photons from the entire sunlight spectrum.
The two substances developed by the researchers as "photon matchmakers" have quite different properties. Whereas one serves as an "antenna" for green light (antenna molecule), the other pairs the photons, connecting the two low-energy green photons into one high-energy blue photon, which it transmits as an emitter (emitter molecule).
This is what happens in detail: first the antenna molecule absorbs a green low-energy photon and passes it to the emitter molecule as a package of energy. Both molecules store the energy one after the other in "excited" states. Then, two of the energy-loaded emitter molecules react with each other - one molecule passes its energy package to the other. This returns one molecule to its low-energy state. The other, conversely, achieves a very high-energy state that stores the double energy package. This state rapidly collapses when the large energy package is sent out in the form of a blue photon. Although this light particle is of a shorter wave length and higher in energy than the green light emitted initially, the end effect is that no energy is generated, but the energy from two photons is combined into one.
The process is very interesting in chemical terms as the molecules must be carefully matched to allow the energy to be transmitted efficiently, and neither the antenna nor the emitter molecules are allowed to lose their energy through shortcuts. The researchers therefore had to synthesize an antenna molecule that absorbed longwave light and store it for so long that the energy could be transferred to an emitter. Only a complex metal organic compound with a platinum atom in a ring-shaped molecule was suitable for this purpose. The emitter molecule, on the other hand, must be able to take the energy package from the antenna and hold on to it until another excited emitter molecule is found for the subsequent photon fusion.
As this procedure allows previously unused parts of sunlight to be used in solar cells, the scientists are hoping that it offers the ideal starting point for more efficient solar cells. To optimize the process and to bring it closer to an application, they are testing new pairs of substances for other colors in the light spectrum and are experimenting with integrating them in a polymer matrix.
Note: This story has been adapted from a news release issued by Max-Planck-Gesellschaft.
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