Graphene will be used in the construction of photovoltaic panels in the future
Flexible, thin, resistant, transparent, waterproof, inexpensive and sustainable. We are talking of graphene, the material of the new millennium that has ancient roots that sink in our daily lives. The history of men is made of discoveries and, occasionally, a new material or chemical element opens the door to new experiments. From the delivery of the Nobel Prize in Physics to Andre Geim and Konstantin Novoselov in 2010, the research did not stop and new findings bode well for future applications of the great-grandson of graphite.
BY GRAPHITE graphene
The discovery and the Nobel
Graphite is a mineral that occurs in nature in the form of leaf-like masses or sheets of black color. Its atomic structure is made up of carbon atoms that form a lattice of hexagonal cells in layers and each layer is linked to the other through the Van der Waals forces. Its melting temperature is the highest in nature (melts at 3500 ° C) and is an excellent conductor of electricity and heat.
Graphene is a material obtained in laboratory dall'esfoliazione of graphite and is constituted by one monoatomic layer of carbon, organized according to a crystalline structure of hexagonal cells. Its reduced thickness of 0.3 nm allows us to define a two-dimensional material.
Exfoliate graphite is a task we do every day, drawing or writing, but only in 2004 Geim and Novoselov were able to demonstrate the ability to isolate the thinnest material in the world through the 'exfoliation of a graphite block. The device obtained, based on a single-layer graphene, opened the way for the experimental validation of the theories and techniques on the mechanical properties of the material.
Preparation Techniques
The exfoliation of graphite can occur in two ways:
- For mechanical exfoliation, or by applying a force to the surface of the graphite crystals to unplug the crystalline layers and obtain the single layer. Geim and Novoselov have simplified this method by using the simple tape. This is the method of scotch-tape peel and consists of graphite with adhesive tape on which the flakes are deposited. The tape is folded back on itself and then reopened several times. At the end of the process on the tape remains a very thin layer of graphene that is transferred onto an insulating substrate;
- For chemical exfoliation, ie with the use of chemical solvents that infiltrate between the carbon layers by exploiting the hydrophilicity of the graphite itself. The subsequent immersion in an ultrasonic bath allows you to break the chemical bonds that rule the layers together. In a few hours you can get the graphene sheets in liquid suspension, then joined into a larger sheet by spraying the liquid on a substrate.
The latter method allows to work with a material with more stable characteristics and facilitates large-scale production, that instead the mechanical method does not facilitate. However, the problem that scientists are solving is linked precisely to the charges, monetary and environmental, the latter procedure. In fact, a group of scholars of Toyohashi University of Technology led by Yuji Tanizawa managed to "tame" the microorganisms collected in a river near the university campus, in Aichi Prefecture, using them to produce graphene sheets. The new method, presented on the Journal of Physics Conference Series, could be defined as a method dell'esfoliazione organic because it uses a hybrid process that combines chemical and biological agents and processes that answers all the problems related to the production of sheets of high quality, low cost, and in full respect of the environment.
FUTURE APPLICATIONS: THE ELECTRICAL CIRCUIT FOR SOLAR PANELS
The low cost of graphite, but poor material abundant in nature and waste product of many chemical processes such as catalytic converters, together with the virtues of graphene make it possible to imagine the many applications proposed by the studies carried out to date. The high conductivity of graphene sheets allow them to store large amounts of energy, making it a supercapacitor. This property together with resistance and thermal stability, make graphene an ideal candidate for the new experiments in electronics, in the production of electrical circuits and computer super fast, and even more resistant phones with batteries and electric cars. Its flexibility also makes us imagine that soon touchscreen handheld and can be easily rolled up or folded. Also, not being a heavy metal, graphite is not toxic.
It is, however, another use most surprising of these sheets: the transparency of graphene allows the incident light to cross and remain unchanged, paving the way for the use of Schottky devices in the field of photovoltaics, also replacing silicon in photovoltaic cells.
In short, the future of photovoltaics has not yet been written but it sure is in the tip of pencil.
12/07/2012
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Translated via software
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Source:
Italian version of CercaGeometra.it