Photovoltaic cells gallium

Gallium arsenide is also used in photovoltaic cells. These devices turn sunlight into electricity. Many people believe that photovoltaic cells will someday replace coal-fired generating and nuclear power plants as the major source of electricity. 

NASA provides spacecraft with power by extensive use of photovoltaic cells. In this application, the lightweight of the cell, coupled with the almost continuous availability of sunlight in space, has made the photovoltaic cell a bargain almost independent of the cost. In space applications, collectors made from single crystals of silicon or gallium arsenide are used. These systems are very expensive. 

Gallium arsenide is a semiconductor material that can be used to manufacture photovoltaic cells. The gallium and arsenic needed to make these materials are rare compared to silicon. It is difficult, and thus expensive to produce semiconductor gallium arsenide of proper purity for photovoltaic cells. Despite the higher cost of gallium arsenide, it is of great interest because test photovoltaic cells have shown sunlight to electricity efficiencies of over 20%. They have found some use in space applications. 

Solar cells (photovoltaic cells) convert simlight to electricity. Photovoltaic cells are made of semiconductor materials such as silicon and gallium arsenide. When light strikes the cell, photons are absorbed within the semiconductor and create electron-hole pairs that move within the cell. This generates the energy that is used to power space vehicles. 

Abstract Photovoltaic cells have been dominated so far by solid state p-n junction devices made from silicon or gallium arsenide wavers or thin film embodiments based on amorphous silicon, CdTe and copper indium gallium diselenide (CIGS) profiting from the experience and material availability of the semiconductor industry. Recently there has been a surge of interest for devices that are based on nanoscale inorganic or organic semiconductors commonly referred to as bulk junctions due to their interconnected three-dimensional structure. The present chapter describes the state of the art of the academic and industrial development of nanostructured solar cells, with emphasis in the development of the dye-sensitized nanocristalline solar cell. 

Thin Film - A layer of semiconductor material, such as copper indium diselenide or gallium arsenide, a few microns or less in thickness, used to make solar photovoltaic cells. 

Photovoltaic (PV) solar cells, which convert incident solar radiation directly into electrical energy, today represent the most common power source for Earth-orbiting spacecraft, such as the International Space Station, where a photovoltaic engineering testbed (PET) is actually assembled on the express pallet. The solid-state photovoltaics, based on gallium arsenide, indium phosphide, or silicon, prove capable, even if to different extents and with... 

Cells made from GaAs are more costly than silicon cells, because the production process is not as well developed, and gallium and arsenic are not abundant materials. GaAs cells have been used when very high efficiency is needed regardless of cost such as required in space applications. They were also used in the Sunraycer, a photovoltaic-powered electric car, which won the Pentax World Solar Challenge race for solar-powered vehicles in 1987. It ran the 3000-km from Darwin to Adelaide, Australia at an average day time speed of 66-km per hour. The 1990 race was won by a... 

Donald Osborn, supervisor of the solar program of the Sacramento Municipal Utility District in California, says that analysts expect the price of the price of a single-crystal module to be as low as 2 per watt by 2010. Osborne says that advanced thin-film cells made of exotic materials such as gallium arsenide have shown laboratory efficiencies as high as 28 percent with concentrated sunlight.18 Some thin-film photovoltaic modules are expected to cost as little as 1.25 per watt by 2010. 

There is a problem with the widespread use of arsenic, cadmium, and selenium in electronic and photovoltaic devices. Cadmium mercury telluride is used in infrared-sensing night goggles. Cadmium sulfide, cadmium selenide, gallium arsenide, and analogues, are used in solar cells. If their use becomes widespread, then an efficient system of collecting used cells for reprocessing will be needed. Some workers feel that it will be better to use nontoxic silicon cells wherever possible. (Solar cells are discussed in Chap. 15.)... 

---