Scientists at the Massachusetts Institute of Technology have successfully coated paper with a solar cell, part of a suite of research projects aimed at energy breakthroughs.

Susan Hockfield, MIT’s president, and Paolo Scaroni, CEO of Italian oil company Eni, on Tuesday officially dedicated the Eni-MIT Solar Frontiers Research Center. Eni invested $5 million into the center, which is also receiving a $2 million National Science Foundation grant, said Vladimir Bulovic, the center’s director.

The printed solar cells, which Bulovic showed at a press conference Tuesday, are still in the research phase and are years from being commercialized.

However, the technique, in which paper is coated with organic semiconductor material using a process similar to an inkjet printer, is a promising way to lower the weight of solar panels. “If you could use a staple gun to install a solar panel, there could be a lot of value,” Bulovic said.

The materials MIT researchers used are carbon-based dyes and the cells are about 1.5 percent to 2 percent efficient at converting sunlight to electricity. But any material could be used if it can be deposited at room temperature, Bulovic said. “Absolutely, the trick was coming up with ways to use paper,” he said.

MIT professor Karen Gleason headed the research and has submitted a paper for scientific review but it has not yet been published. MIT and Eni said this is the first time a solar cell has been printed on paper.

During the press conference, Scaroni said that Eni is funding the center because the company understands that hydrocarbons will eventually run out and believes that solar can be a replacement. At the same time, he said, current technologies are not sufficient.

“We are not very active (in alternative energy) today because we don’t believe today’s technologies are the answer of our problems,” he said.

Quantum dots

The paper solar cells are one of many avenues being pursued around nanoscale materials at the Eni-MIT Solar Frontiers Center. Layers of these materials could essentially be sprayed using different manufacturing techniques to make a thin-film solar cell on a plastic, paper, or metal foils.

Silicon, the predominant material for solar cells, is durable and is made from abundant materials. Many companies sell or are developing thin-film solar cells, which are less efficient but are cheaper to manufacture.

During a tour, Bulovic showed one of the center’s labs, where researchers use a laser to blast light at nanomaterials for picoseconds. A picosecond is one trillionth of a second. The laser provides data on how the light excites electrons in the material, which will provide clues as to whether it will make a good solar cell material, he explained.

MIT is focusing much of its effort on quantum dots, or tiny crystals that are only a few nanometers in size. A human hair is about 50,000 to 100,000 nanometers thick.

By using different materials and sizes, researchers can fine-tune the colors of light that quantum dots can absorb, a way of isolating good candidates for quantum dot solar cells.

Researchers at the center are also looking at different molecules or biological elements which can act as solar cell material. These cheap thin-film materials can be used on their own or added to silicon-based solar panels to enhance the efficiency, Bulovic said.

If 0.3 percent of the U.S. were covered with photovoltaics with 10 percent efficiency, solar power could produce three times the country’s needs, including a transition to electric vehicles, Bulovic said. For example, the easement strip on highways could be coated with material that could capture energy from the sun.

But don’t expect a revolution in solar power tomorrow.

“I’m giving you a whole bunch of hype,” Bulovic said while explaining solar’s potential during the tour. “It usually takes 10 years from the time between when you invent something and you commercialize it.” He estimated that many of the technologies in the labs were in the first three years of a five-to-seven-year development cycle.

Source: CNN

By growing arrays of silicon wires in a polymer substrate, researchers have demonstrated what they say are flexible solar cells that absorb up to 96 percent of incident light.

California Institute of Technology (Caltech) researchers said the wires are made up of 98 percent plastic, potentially lowering the cost of photovoltaics by using just 1/50th the amount of semiconductor material used today. In tests, the experimental solar cells demonstrated over 90 percent quantum efficiency, compared with 25 percent for the best silicon solar cells.

“By developing light-trapping techniques for relatively sparse wire arrays, not only did we achieve suitable absorption, but we also demonstrated effective optical concentration,” claimed Harry Atwater, director of Caltech’s Resnick Institute.

The silicon wires measure just 1 micron in diameter, but can be as long as 100 microns and can be embedded in a transparent polymer. Light is converted into electricity only inside the wires, but light not immediately absorbed bounces around inside the matrix until it enters another wire. The result, researchers said, is both high concentration and high efficiency in the material.

Solar cells based on the technique could potentially be very inexpensive to manufacture since only 2 percent of the materials are expensive semiconductors while the remainder is made from inexpensive plastic.

The new material is about the same overall thickness as a conventional solar cells–about 100 microns–but contain as much silicon as a solar cell measuring just 2 microns in thickness.

Atwater said he is now working to increase the operating voltage and size of the solar cells so that they can eventually be manufactured in flexible sheets using inexpensive roll-to-roll fabrication equipment.

Funding for the Caltech research was provided by BP, the U.S. Energy Department, the National Science Foundation and the Kavli Nanoscience Institute at Caltech.

Source: Low-cost, more efficient solar cells mostly plastic (EE Times)

An Avondale, AZ woman is in danger of losing her home because city code enforcement officers condemned her home for lack of  Store bought electricity. Christine Stevens, who has been laid from her job as a risk compliance officer for Wells Fargo Bank in January 2009, switched to solar generated electricity to save money.

Avondale city officials condemned her home because it violated building codes. The city  says it was condemned due to a a health and safety concern because Avondale homes are required to have heating systems and a running refrigerator.

Avondale condemns home: Solar, batteries insufficient (AZCentral.com)