Tuesday, October 19, 2010
Use of graphene photovoltaics as alternate source of energy
Could you imagine people powering their cell phone or music/video device while jogging on a sunny day?
A University of Southern California team has produced flexible transparent carbon atom films that may have great potential for a new breed of solar cells. Inside a paper recently published in the journal ACS Nano, researchers stated that organic photovoltaic (OPV) cells have been proposed as an approach to create low priced energy due to their ease of manufacture, light weight, and compatibility with flexible substrates.
This work shows that graphene, a highly conductive and highly transparent kind of carbon composed of atoms-thick sheets of carbon atoms, has high possibility to fill this role.While graphene’s existence has been known for decades, it has only been studied extensively since 2004 because of the impracticality of manufacturing it in high quality and quantity.
The University of southern California team has produced graphene/polymer sheets ranging in sizes nearly 150 square centimeters that in turn may be used to create dense arrays of flexible organic photovoltaic (OPV) cells.These organic photovoltaic (OPV) devices convert solar radiation to electricity, but not as efficiently as silicon cells.
The power provided by sunlight on a sunny day is around 1,000 watts per meter square, for every 1,000 watts of sunlight that hits a square meter part of the standard silicon solar cell, 14 watts of electricity will be generated, Organic solar cells are less efficient; their conversion rate for that same 1,000 watts of sunlight in the graphene-based solar cell would be only 1.3 watts.But what graphene organic photovoltaic (OPV) lack in efficiency, can potentially be compensated by its lower price and, greater physical flexibility.
Researchers think it may eventually be possible to cover with inexpensive solar cell layers extensive areas like newspapers, magazines or power generating clothing.In the meanwhile Prof. Ruoff and his colleagues of the mechanical engineering department at the University of Texas at Austin, are studying the basic science in the development of graphene-based ultracapacitors for usage in electronics and other fields.Prof. Ruoff says batteries are relatively slow, they can store energy but require some time to charge up, and then they distribute energy slowly, over time.
Ultracapacitors can be charged rapidly, in seconds, and discharge quickly, but, right now, they can’t store very much electrical energy.The development of stable and cheaper ultracapacitors should be a key step in using wind or solar-generated power, especially if researchers can find solutions to enable capacitors to store energy longer, that is not yet possible.
Even with their current storage capacity, the graphene devices could provide quick energy when needed in certain situations on the eco-friendly way.They may be used, for instance, to absorb the heat generated in braking an automobile or train, and store it for a short time, and employ it for the electrical needs of the vehicle (i.e. starting the car or acceleration)
source: http://www.comptalks.com/use-of-graphene-photovoltaics-as-alternate-source-of-energy/
A University of Southern California team has produced flexible transparent carbon atom films that may have great potential for a new breed of solar cells. Inside a paper recently published in the journal ACS Nano, researchers stated that organic photovoltaic (OPV) cells have been proposed as an approach to create low priced energy due to their ease of manufacture, light weight, and compatibility with flexible substrates.
This work shows that graphene, a highly conductive and highly transparent kind of carbon composed of atoms-thick sheets of carbon atoms, has high possibility to fill this role.While graphene’s existence has been known for decades, it has only been studied extensively since 2004 because of the impracticality of manufacturing it in high quality and quantity.
The University of southern California team has produced graphene/polymer sheets ranging in sizes nearly 150 square centimeters that in turn may be used to create dense arrays of flexible organic photovoltaic (OPV) cells.These organic photovoltaic (OPV) devices convert solar radiation to electricity, but not as efficiently as silicon cells.
The power provided by sunlight on a sunny day is around 1,000 watts per meter square, for every 1,000 watts of sunlight that hits a square meter part of the standard silicon solar cell, 14 watts of electricity will be generated, Organic solar cells are less efficient; their conversion rate for that same 1,000 watts of sunlight in the graphene-based solar cell would be only 1.3 watts.But what graphene organic photovoltaic (OPV) lack in efficiency, can potentially be compensated by its lower price and, greater physical flexibility.
Researchers think it may eventually be possible to cover with inexpensive solar cell layers extensive areas like newspapers, magazines or power generating clothing.In the meanwhile Prof. Ruoff and his colleagues of the mechanical engineering department at the University of Texas at Austin, are studying the basic science in the development of graphene-based ultracapacitors for usage in electronics and other fields.Prof. Ruoff says batteries are relatively slow, they can store energy but require some time to charge up, and then they distribute energy slowly, over time.
Ultracapacitors can be charged rapidly, in seconds, and discharge quickly, but, right now, they can’t store very much electrical energy.The development of stable and cheaper ultracapacitors should be a key step in using wind or solar-generated power, especially if researchers can find solutions to enable capacitors to store energy longer, that is not yet possible.
Even with their current storage capacity, the graphene devices could provide quick energy when needed in certain situations on the eco-friendly way.They may be used, for instance, to absorb the heat generated in braking an automobile or train, and store it for a short time, and employ it for the electrical needs of the vehicle (i.e. starting the car or acceleration)
source: http://www.comptalks.com/use-of-graphene-photovoltaics-as-alternate-source-of-energy/
Labels: Graphene, photovoltaics
Graphene 100 Times Stronger Than Steel
Graphite, a form of carbon, has always been a strange substance. It is one of the few materials that doesn't expand when heated or shrink when cooled (i.e., it has zero coefficient of linear expansion). It isn't a metal, but it conducts electricity like a metal. And, the strangest thing of all: in a universe that is essentially three dimensional, graphite forms a unique two-dimensional crystal (i.e., a crystal that is a sheet rather than a three dimensional shape). The graphite we are all familiar with, such as a pencil lead, is simply a pile of these crystal sheets. When you rub a pencil lead it feels oily. It's not. What you feel is the movement of these crystal sheets, which makes for the slipperiness.
These crystal sheets are very thin - only one atom thick. It would take a stack of 177 million or so of them to make an inch. No one was ever able to split off and examine a single sheet - until a pair of Nobel Prize winning scientists figured out how.
And, what they discovered was truly amazing. Graphene, the name given to a single sheet of graphite turns out to be the strongest material known - 100 times stronger than steel. It is not just a good conductor of electricity; it is the best-known conductor of electricity. And, it is slippery, very slippery.
These crystal sheets are very thin - only one atom thick. It would take a stack of 177 million or so of them to make an inch. No one was ever able to split off and examine a single sheet - until a pair of Nobel Prize winning scientists figured out how.
And, what they discovered was truly amazing. Graphene, the name given to a single sheet of graphite turns out to be the strongest material known - 100 times stronger than steel. It is not just a good conductor of electricity; it is the best-known conductor of electricity. And, it is slippery, very slippery.
Labels: Graphene, Graphite, Stronger Than Steel
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