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

ScienceDaily (July 4, 2011) — A scientific advance in renewable energy which promises a revolution in the ease and cost of using solar cells, has been announced on July 4, 2011. 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.

The study, published in the journal Advanced Energy Materials, paves the way for new solar cell manufacturing techniques and the promise of developments in renewable solar energy. Scientists from the Universities of Sheffield and Cambridge used the ISIS Neutron Source and Diamond Light Source at STFC Rutherford Appleton Laboratory in Oxfordshire to carry out the research.

Plastic (polymer) solar cells are much cheaper to produce than conventional silicon solar cells and have the potential to be produced in large quantities. The study showed that when complex mixtures of molecules in solution are spread onto a surface, like varnishing a table-top, the different molecules separate to the top and bottom of the layer in a way that maximises the efficiency of the resulting solar cell.

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 nano-scale (60 nano-meters) 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."

Dr. Robert Dalgliesh, one of the ISIS scientists involved in the work, said, "This work clearly illustrates the importance of the combined use of neutron and X-ray scattering sources such as ISIS and Diamond in solving modern challenges for society. Using neutron beams at ISIS and Diamond's bright X-rays, we were able to probe the internal structure and properties of the solar cell materials non-destructively. By studying the layers in the materials which convert sunlight into electricity, we are learning how different processing steps change the overall efficiency and affect the overall polymer solar cell performance. "

"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."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Science and Technology Facilities Council (STFC).

Journal Reference:

Paul A. Staniec, Andrew J. Parnell, Alan D. F. Dunbar, Hunan Yi, Andrew J. Pearson, Tao Wang, Paul E. Hopkinson, Christy Kinane, Robert M. Dalgliesh, Athene M. Donald, Anthony J. Ryan, Ahmed Iraqi, Richard A. L. Jones, David G. Lidzey. The Nanoscale Morphology of a PCDTBT:PCBM Photovoltaic Blend. Advanced Energy Materials, 2011; DOI: 10.1002/aenm.201100144

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Single-crystal arrays of graphene: Advance in efforts to develop a replacement for silicon in high-performance electronics

ScienceDaily (June 2, 2011) — University of Houston researchers have developed a method for creating single-crystal arrays of the material graphene, an advance that opens the possibility of a replacement for silicon in high-performance computers and electronics.

The work by UH researchers and their collaborators is featured on the cover of the June issue of Nature Materials.

Graphene is a one-atom-thick layer of carbon that was first fabricated in 2004. Single-crystal arrays of the material could be used to create a new class of high-speed transistors and integrated circuits that use less energy than silicon electronics because graphene conducts electricity with little resistance or heat generation.

But the industry needs a reliable and defect-free method for manufacturing large quantities of single crystals of graphene. The development reported in Nature Materials marks a step towards perfecting such a method.

"Using these seeds, we can grow an ordered array of thousands or millions of single crystals of graphene," said Qingkai Yu, the paper's first author. Yu developed the single-crystal growth process at the UH Center for Advanced Materials (CAM), where he was a research assistant professor of electrical and computer engineering.

"We hope the industry will look at these findings and consider the ordered arrays as a possible means of fabricating electronic devices," said Yu, who is now an assistant professor at Texas State University in San Marcos and remains a project leader at CAM.

Yu and Steven Pei, UH professor of electrical and computer engineering and CAM's deputy director, invented the graphene seeded-growth technique that UH patented in 2010.

"There is still a long way to go. However, this development makes the fabrication of integrated circuits with graphene transistors possible. This may actually be the first viable integrated circuit technology based on nano-electronics," Pei said.

Yong P. Chen, an assistant professor of nanoscience and physics at Purdue University, was the paper's co-corresponding author.

At CAM, single-crystal graphene arrays were grown on top of a copper foil inside a chamber containing methane gas using a process called chemical vapor deposition. This process was pioneered by Yu at CAM in 2008 and is now widely accepted as the standard method to create large-area graphene films for potential applications in touch-screen displays, e-books and solar cells.

"Graphene isn't there yet, in terms of high quality mass production like silicon, but this is a very important step in that direction," said Chen, who led the graphene characterization efforts at Purdue.

In addition to Yu and Pei, UH graduate students Wei Wu and Zhihua Su, postdoctoral researchers Zhihong Liu and Peng Peng and assistant professor Jiming Bao along with Chen and nine other researchers from Purdue University, Brookhaven National Laboratory, Argonne National Laboratories and Carl Zeiss SMT Inc. co-authored the paper.

Last year, two scientists received the Nobel Prize in physics for discovering graphene. At that time, Yu was working at CAM to develop ways to produce mass quantities of high-quality graphene.

The findings reported in Nature Materials demonstrated that researchers could control the growth of the ordered arrays. The researchers also were the first to demonstrate the electronic properties of individual grain boundaries.

The research was supported through a variety of funding sources, including the National Science Foundation, the U.S. Department of Energy, the Department of Homeland Security, the Defense Threat Reduction Agency, IBM Inc., the Welch Foundation, the Miller Family Endowment and Midwest Institute for Nanoelectronics Discovery.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Houston.

Journal Reference:

Qingkai Yu, Luis A. Jauregui, Wei Wu, Robert Colby, Jifa Tian, Zhihua Su, Helin Cao, Zhihong Liu, Deepak Pandey, Dongguang Wei, Ting Fung Chung, Peng Peng, Nathan P. Guisinger, Eric A. Stach, Jiming Bao, Shin-Shem Pei, Yong P. Chen. Control and characterization of individual grains and grain boundaries in graphene grown by chemical vapour deposition. Nature Materials, 2011; 10 (6): 443 DOI: 10.1038/nmat3010

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Single-crystal arrays of graphene: Advance in efforts to develop a replacement for silicon in high-performance electronics

ScienceDaily (June 2, 2011) — University of Houston researchers have developed a method for creating single-crystal arrays of the material graphene, an advance that opens the possibility of a replacement for silicon in high-performance computers and electronics.

The work by UH researchers and their collaborators is featured on the cover of the June issue of Nature Materials.

Graphene is a one-atom-thick layer of carbon that was first fabricated in 2004. Single-crystal arrays of the material could be used to create a new class of high-speed transistors and integrated circuits that use less energy than silicon electronics because graphene conducts electricity with little resistance or heat generation.

But the industry needs a reliable and defect-free method for manufacturing large quantities of single crystals of graphene. The development reported in Nature Materials marks a step towards perfecting such a method.

"Using these seeds, we can grow an ordered array of thousands or millions of single crystals of graphene," said Qingkai Yu, the paper's first author. Yu developed the single-crystal growth process at the UH Center for Advanced Materials (CAM), where he was a research assistant professor of electrical and computer engineering.

"We hope the industry will look at these findings and consider the ordered arrays as a possible means of fabricating electronic devices," said Yu, who is now an assistant professor at Texas State University in San Marcos and remains a project leader at CAM.

Yu and Steven Pei, UH professor of electrical and computer engineering and CAM's deputy director, invented the graphene seeded-growth technique that UH patented in 2010.

"There is still a long way to go. However, this development makes the fabrication of integrated circuits with graphene transistors possible. This may actually be the first viable integrated circuit technology based on nano-electronics," Pei said.

Yong P. Chen, an assistant professor of nanoscience and physics at Purdue University, was the paper's co-corresponding author.

At CAM, single-crystal graphene arrays were grown on top of a copper foil inside a chamber containing methane gas using a process called chemical vapor deposition. This process was pioneered by Yu at CAM in 2008 and is now widely accepted as the standard method to create large-area graphene films for potential applications in touch-screen displays, e-books and solar cells.

"Graphene isn't there yet, in terms of high quality mass production like silicon, but this is a very important step in that direction," said Chen, who led the graphene characterization efforts at Purdue.

In addition to Yu and Pei, UH graduate students Wei Wu and Zhihua Su, postdoctoral researchers Zhihong Liu and Peng Peng and assistant professor Jiming Bao along with Chen and nine other researchers from Purdue University, Brookhaven National Laboratory, Argonne National Laboratories and Carl Zeiss SMT Inc. co-authored the paper.

Last year, two scientists received the Nobel Prize in physics for discovering graphene. At that time, Yu was working at CAM to develop ways to produce mass quantities of high-quality graphene.

The findings reported in Nature Materials demonstrated that researchers could control the growth of the ordered arrays. The researchers also were the first to demonstrate the electronic properties of individual grain boundaries.

The research was supported through a variety of funding sources, including the National Science Foundation, the U.S. Department of Energy, the Department of Homeland Security, the Defense Threat Reduction Agency, IBM Inc., the Welch Foundation, the Miller Family Endowment and Midwest Institute for Nanoelectronics Discovery.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Houston.

Journal Reference:

Qingkai Yu, Luis A. Jauregui, Wei Wu, Robert Colby, Jifa Tian, Zhihua Su, Helin Cao, Zhihong Liu, Deepak Pandey, Dongguang Wei, Ting Fung Chung, Peng Peng, Nathan P. Guisinger, Eric A. Stach, Jiming Bao, Shin-Shem Pei, Yong P. Chen. Control and characterization of individual grains and grain boundaries in graphene grown by chemical vapour deposition. Nature Materials, 2011; 10 (6): 443 DOI: 10.1038/nmat3010

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here