Flexible Solar Cells on Paper by MIT

We’ve seen several different examples of printable solar cells in the past, however MIT engineers just unveiled a new type of cell that can be printed onto paper or fabric.

Read more: MIT Unveils Flexible Solar Cells Printed on Paper | Inhabitat - Green Design Will Save the World.

Video: Dynamic folding of a paper solar cell circuit.

'Cling-film' solar cells could lead to advance in renewable energy

'Cling-film' solar cells could lead to advance in renewable energy

(PhysOrg.com) -- A scientific advance in renewable energy which promises a revolution in the ease and cost of using solar cells, has been announced today. A new study shows that even when using very simple and inexpensive manufacturing methods - where flexible layers of material are deposited over large areas like cling-film - efficient solar cell structures can be made.

Excerpt from the article:

"Dr Andrew Parnell of the University of Sheffield said, "Our results give important insights into how ultra-cheap solar energy panels for domestic and industrial use can be manufactured on a large scale. Rather than using complex and expensive fabrication methods to create a specific semiconductor nanostructure, high volume printing could be used to produce nanoscale (60 nanometers) films of solar cells that are over a thousand times thinner than the width of a human hair. These films could then be used to make cost-effective, light and easily transportable plastic solar cell devices such as solar panels."

"Over the next fifty years society is going to need to supply the growing energy demands of the world's population without using fossil fuels, and the only renewable energy source that can do this is the Sun", said Professor Richard Jones of the University of Sheffield. "In a couple of hours enough energy from sunlight falls on the Earth to satisfy the energy needs of the Earth for a whole year, but we need to be able to harness this on a much bigger scale than we can do now. Cheap and efficient polymer solar cells that can cover huge areas could help move us into a new age of renewable energy."

Solar cells
Photovoltaics are semiconductor devices that are used to generate low-cost renewable energy - most commonly as solar panels. When sunlight hits a photovoltaic cell, it is absorbed and its energy is converted into an electrical current. Most photovoltaic devices are made with silicon; however, devices can also be made from plastic (organic photovoltaic devices).
Plastic films can be deposited from solution by low-cost, roll to roll printing techniques resulting in significant overall savings in energy and cost. This is where the film is put on a roll and goes through a series of processes similar to the way newspapers are printed and taken off a roll at the end. There are currently products using this type of technology. To increase usage further, however, the technology needs to be more efficient. Polymer solar cells are currently 7-8% efficient.The next step is to develop cells which are 10% efficient or more for commercial viability.
The materials used in the research carried out by the collaboration are called PCDTBT (poly [N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di- 2-thienyl- 2′,1′,3′-benzothiadiazole): PCBM ([6,6]- phenyl-C61-butyric acid methylester), a material based on Nobel-prize-winning (Chemistry 1996) work of Professor Richard Smalley and Professor Harry Kroto (amongst others) on the C60 Buckminsterfullerene or buckyball form of carbon.Bright X-rays using instruments at Diamond Light Source were used to study the crystallinity of the material; neutrons at ISIS were used to examine the material's composition profile.

More information: The research is published in Advanced Energy Materials, volume 1, issue 4 July 2011.

Inkjet printing could change the face of solar energy industry

Inkjet printing could change the face of solar energy industry

Inkjet printers, a low-cost technology that in recent decades has revolutionized home and small office printing, may soon offer similar benefits for the future of solar energy.

From : http://www.physorg.com/news/2011-06-inkjet-solar-energy-industry.html

Engineers at Oregon State University have discovered a way for the first time to create successful "CIGS" solar devices with inkjet printing, in work that reduces raw material waste by 90 percent and will significantly lower the cost of producing solar energy cells with some very promising compounds.
High performing, rapidly produced, ultra-low cost, thin film solar electronics should be possible, scientists said.
The findings have been published in Solar Energy Materials and Solar Cells, a professional journal, and a patent applied for on the discovery. Further research is needed to increase the efficiency of the cell, but the work could lead to a whole new generation of solar energy technology, researchers say.
"This is very promising and could be an important new technology to add to the solar energy field," said Chih-hung Chang, an OSU professor in the School of Chemical, Biological and Environmental Engineering. "Until now no one had been able to create working CIGS solar devices with inkjet technology."
Part of the advantage of this approach, Chang said, is a dramatic reduction in wasted material. Instead of depositing chemical compounds on a substrate with a more expensive vapor phase deposition – wasting most of the material in the process – inkjet technology could be used to create precise patterning with very low waste.
"Some of the materials we want to work with for the most advanced solar cells, such as indium, are relatively expensive," Chang said. "If that's what you're using you can't really afford to waste it, and the inkjet approach almost eliminates the waste."
One of the most promising compounds and the focus of the current study is called chalcopyrite, or "CIGS" for the copper, indium, gallium and selenium elements of which it's composed. CIGS has extraordinary solar efficiency – a layer of chalcopyrite one or two microns thick has the ability to capture the energy from photons about as efficiently as a 50-micron-thick layer made with silicon.

In the new findings, researchers were able to create an ink that could print chalcopyrite onto substrates with an inkjet approach, with a power conversion efficiency of about 5 percent. The OSU researchers say that with continued research they should be able to achieve an efficiency of about 12 percent, which would make a commercially viable solar cell.
In related work, being done in collaboration with Greg Herman, an OSU associate professor of chemical engineering, the engineers are studying other compounds that might also be used with inkjet technology, and cost even less.
Some approaches to producing solar cells are time consuming, or require expensive vacuum systems or toxic chemicals. OSU experts are working to eliminate some of those roadblocks and create much less costly solar technology that is also more environmentally friendly. New jobs and industries in the Pacific Northwest could evolve from such initiatives, they say.
If costs can be reduced enough and other hurdles breached, it might even be possible to create solar cells that could be built directly into roofing materials, scientists say, opening a huge new potential for solar energy.
"In summary, a simple, fast, and direct-write, solution-based deposition process is developed for the fabrication of high quality CIGS solar cells," the researchers wrote in their conclusion. "Safe, cheap, and air-stable inks can be prepared easily by controlling the composition of low-cost metal salt precursors at a molecular level."