A NEW GENERATION OF SOLAR CELLS

In 2010 many institutions and companies are developing, testing, and manufacturing a new generation of solar cells. Traditional solar cells are made from crystalline silicon, which has been in high demand, at times resulting in a shortage of crystalline silicon supply throughout the world, and which is a high-cost material to purchase. Therefore, the solar photo voltaic industry is researching and developing non-silicon-based technology, including thin-film solar cells.  

Thin-Film Solar Cells 

Solar engineers refer to second-generation solar cells as thin-film solar cells. Materials used in the production of the thin fi lms include semiconductor materials, such as copper indium diselenide (CuInSe 2  or “CIS”), gallium arsenide, and cadmium telluride. 

Engineer Steve Robbins displays a sheet of “thin film” solar cells at the National Renewable Energy Laboratory in Golden, Colorado, in March 2009. Thin film solar panels are relatively low in cost and their flexible design makes them highly adaptable. (John Moore/Getty Images)


 The term  thin film  refers not to the thinness of the film, but to the manufacturing process used to produce the solar cells. Th in-film cells are deposited in very thin, consecutive layers of atoms, molecules, or ions onto wafer-like material. Th e finished solar cell is only a few micrometers or nanometers thick.  

Thick versus Thin: Any Differences? 

Th in-film cells have some advantages over the thick-film silicon cells. For example, less material is needed in the manufacturing of thin-film cells. A thin cell is usually only 1–10 micrometers thick, whereas thick crystalline films typically are 100–300 micrometers thick and have to be cut from ribbons. 

Also, thin-film cells can usually be manufactured in a continuous, automated production process. Automated processes can assure improved product quality, lower operating costs, and better safety conditions. Finally, the thin-fi lm cells can be deposited on flexible materials such as ultra thin glass, stainless steel, or plastic in any shape. Because of their flexibility, thin-film solar cells can be used as rooftop shingles, on the exterior part of a building or facade, or in the glazing for skylights.  

How Do Thin-Film Solar Cells Produce Electricity? 

Under a microscope the thin-fi lm cells have two layers sandwiched together. The top layer is made of a different semiconductor material than the material used for the bottom semiconductor layer. Th e top layer is called an N-type—the negative charge. Chemicals in this layer allow the sunlight through to the absorbing layer, called the P-type—the positive charge. When the sunlight passes through a conducting chemical on the surface, the sunlight makes contact with a series of chemicals (i.e., indium, copper, gallium, and diselenide) that allow electrons to fl ow through a wire to create electricity from the N-type and P-type. 


John F. Mongillo
A Student Guide to Energy 
Copyright 2011
Greenwood Publishing Group
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