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Turning Sunlight Into Electricity!
Solar Cells convert light energy into electricity at
the atomic level. It was first discovered in 1839, the process of producing electric current in a solid material with the aid of sunlight wasn't truly under- stood for more than a hundred years.
Throughout the second half of the 20th century, the science has been refined and process has been more fully explained. As a result the cost of these devices has put them into the mainstream of modem energy producers. This was caused in part by advances in technology, where PV conversion efficiencies have been improved.
Solar Cell Materials
The most important parts of a solar cell are the semiconductor layers, this is where the electron current is created. There are a number of different materials available for making these semiconducting layers, and each has benefits and drawbacks. Unfortunately, there is no one ideal material for all types of cells and applications.
In addition to the semiconducting materials, solar cells consist of a top metallic grid or other electrical contact to collect electrons from the semiconductor and transfer them to the external load, and a back contact layer to complete the electrical circuit.
Then, on top of the complete cell is typically a glass
cover or other type of transparent encapsulant to seal the cell and keep weather out, and a anti-
reflective coating to keep the cell from reflecting the light back away from the cell. A typical solar cell consists of a cover glass, a anti-reflective layer, a
front contact to allow the electrons to enter a circuit and a back contact to allow them to complete the circuit, and the semiconductor layers where the electrons begin to complete there voyages!
Scientists in Arizona are using screen-printing, a
technique developed for printing fabrics, paper and to produce plastic, glass and metal solar cells.
The basic materials of a photovoltaic cell (solar cell) are inexpensive. The organic manufactured by Ghassan Jabbour and colleagues at the University of Arizona in Tucson have about 11/4 of the efficiency
of commercial silicon solar cells, which turn 10-20 per cent of light energy into electricity. But, being cheap to produce, they can make up the loss in quantity what they lack in quality. Now the Japan screen printed solar cells are even better than that!
For more info contact: Matsushita Electric Industrial co. LTD, Osaka. Japan
In conventional Screen - printing, a taut piece of screen mesh fabric is stretched over a wood frame,
you can buy the screens already made and the materials from any screen printing shop or screen printing supply company in your area or on the internet. Also you might want to check with your local art store, sometimes they have full kits etc...
The screen is then masked off using masking tape,
For example: a 5" x 5" square area. the screen outside of the masking tape is then coated with a block out
A Screen printing press, the wood frame is the screen
An example of a Silicon cell
liquid or paint, this is so when you apply your semiconducting ink that you mixe, it will go through just the area that you masked off when you apply a rubber squeegee to it. The
screen can then be placed on any table top and hinges attached to the back of the wood frame and the table, this will insure the screen can move up and down. Then get a small wood paint stick and using a small nail, hammer one end to the front side of wood frame. This will be your kick leg and will help keep your screen in an upward position when needed. Take a 5" x 5" piece of glass and place it right under the open 5" x 5" area of the open screen mesh. When the leg is flipped back the screen comes down and you grab
your rubber and wood handled squeegee and with the ink in front of your rubber squeegee pull toward you applying pressure so ink will go through screen, once you have passed by
the 5" x 5" area then flip the screen back up and reverse squeegee to flood the screen for the