Nanorods grown on the aluminum foil can produce solar cells
U.S. researchers have developed a new type of solar cell technology, such solar cells can be grown on the aluminum foil to make vertical nanorods, the whole battery packaged in a transparent gel after the polymer can produce flexible solar cells, cost less than conventional silicon solar cells.
Led the research, the University of California professor of electrical engineering and computer science, said Ali Jewitt, and compared to traditional silicon and thin film batteries, nano-column technology allows researchers to use more low-cost and low quality materials. More importantly, the technology is more suitable for the fabrication of thin aluminum foil solar panels can be curved, thereby reducing manufacturing costs. If successful, the cost of production of monocrystalline silicon solar panels will be as low as 1 / 10.
This solar cell is 500 nm by a high single embedded CdS films made of cadmium telluride, and these two materials are often used in thin film solar cell semiconductor. Jewitt and his colleagues in the "natural materials" published reports that such cells will convert light energy into electrical energy efficiency of up to 6%. Previously, scientists have used this column design, but the method is more expensive, and the photoelectric conversion efficiency of less than 2%.
In conventional solar cells, silicon absorbs light and produce free electrons, these electrons must be trapped in defects or impurities in the material before the arrival circuit. This requires the use of very pure, expensive to manufacture highly efficient crystalline silicon photovoltaic devices.
Nanorods assumed the role of silicon, nano-columns around the absorption of light and produce electronic materials, nano-columns will be transported to the circuit. This design to improve efficiency in two ways: tightly encapsulated nano-columns between columns capture the light, the surrounding material to help absorb more light; e to a very short distance across the nano-column, so there is not much chance of trapped defects in the material. This means you can use low-quality low-cost materials.
Some scientists using different nano-structures to the production of such solar cells. For example, the Harvard University chemistry professor Charles in the Boer developed a silicon-containing different core and concentric layers of silicon nanowires; University of California, Berkeley, Yang Peidong were developed with a zinc oxide nanowire dye sensitized solar cells . These nanowires photoelectric conversion efficiency of solar cells has reached 4%.
Jewitt and his colleagues made use of nano-column cell for the first time by the oxidation of aluminum foil, creating a cyclical distribution of the 200 nm wide holes, these holes as a template for the growth of CdS crystals upright. Then, cadmium telluride, and the top electrode decorated with copper and gold films. They are connected by a glass plate and battery, or to the polymer solution into the top of its bent.
Georgia Institute of Technology professor of materials science and engineering Zhong-Lin Wang commented that the nano-materials, engineering design and manufacturing flexible solar cells flexible and efficient technology integration with a variety of soft substrate, this is an exciting progress. U.S. National Renewable Energy Laboratory is responsible for solar cell research, said physical chemist, this battery to and from silicon, cadmium telluride and other materials made of flexible thin film solar cells to compete, its selling point may not be its flexibility, but the cost advantage.
Currently, researchers are exploring the use of the material can improve the conversion efficiency. For example, the top of the copper - gold layer is only 50% of the transparency, if you can have all of the light through, and its efficiency can be doubled. Therefore, the researchers are planning to use such as indium oxide transparent conductive material. In addition, the use of other semiconductor materials as nano-column and the surrounding material is also considered among the researchers, this production process can be suitable for a wider range of semiconductor materials, other material combinations may also improve efficiency, a more important point is cadmium toxicity problems can be avoided.
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