Cadmium telluride solar cells

From the point of view of II-VI PV devices, by far the most important electrochemical process is the electrodeposition of cadmium telluride for CdSjCdTe heterojunction solar cells. This was the first electrodeposition process to be used in large-scale manufacture of PV devices. BP Solar s Apollo modules, which were fabricated via an electrodeposition route, reached an advanced stage of manufacture, with a module plant coming on line in 1998. However, manufacture of Apollo modules was discontinued later, possibly as a consequence of environmental concerns. Since then. First Solar s cadmium telluride modules, which are fabricated by close space sublimation rather than electrodeposition, have achieved efficiencies of over 12%, with costs poised to fall below 1 per watt peak. 

Mercury Telluride. Compounds of mercury with tellurium have gained importance as semiconductors with appHcations in infrared detection (9) and solar cells (10). The ratio of the components is varied, and other elements such as cadmium, zinc, and indium are added to modify the electronic characteristics. 

Fulop G, Doty M, Meyers P, Betz J, Liu CH (1982) High-efficiency electrodeposited cadmium telluride solar cells. Appl Phys Lett 40 327-328... 

A prime contender for leading thin film technology as applied to solar cells is cadmium telluride (CdTe). Its bandgap is almost ideal for use as a solar cell for energy conversion from the Sun s spectrum. Here, CdTe and cadmium sulfide (CdS) are used to produce a low cost thin film solar cell... 

Although conventional solar cells based on silicon are produced from abundant raw materials, the high-temperature fabrication routes to single-crystal and polycrystalline silicon are energy intensive and expensive. The search for alternative solar cells has therefore focused on thin films composed of amorphous silicon and on other semiconductor heterojunction cells (e.g., cadmium telluride and copper indium... 

Cadmium hydroxide is the anode material of Ag—Cd and Ni—Cd rechargeable storage batteries (see Batteries, SECONDARY cells). Cadmium sulfide, selenide, and especially telluride find utility in solar cells (see Solarenergy). Cadmium sulfide, lithopone, and sulfoselenide are used as colorants (orange, yellow, red) for plastics, glass, glazes, rubber, and fireworks (see Colorants for ceramics Colorants forplastics Pigments). 

McCandless, B.E. Sites, J.R. Cadmium telluride solar cells. In Handbook of Photovoltaic Science and Engineering Luque, A., Hegedus, S., Eds. Wiley Chichester, 2003 617-662. 

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.)... 

The rarest element shown in Figure 1.1 is tellurium, and it is reasonable to suppose that this has implications for the long-term sustainability of cadmium telluride solar cell technology. Sustainability issues of this kind provide the rationale for expansion of the range materials that deserve study for PV applications. A promising new candidate for sustainable PV is Gu2ZnSnS4... 

Photovoltaic cells, or solar cells, work by containing matericadmium telluride, or copper indium selenide whose electrons, ire easily excited by photons from the sun, creating electricity. 

In the form of CdS Sei selenium is used as a red pigment in glass and ceramics. Below its melting point, Se is a semiconductor. Tellurium is used as an additive (<0.1%) to low-carbon steels in order to improve the machine qualities of the metal. This accounts for about half of the world s consumption of tellurium. Catalytic applications are also important, and other applications stem from its semiconducting properties, e.g. cadmium telluride has recently been incorporated into solar cells (see Box 14.3). However, uses of Te are limited, partly because Te compounds are readily absorbed by the body and excreted in the breath and perspiration as foul-smelling organic derivatives. 

Theoretical conversion efficiencies of photovoltaic systems depend on the semiconductor materials used in the cells and on the ambient tanperatuie. The materials currently used to make photovoltaic cells can be grouped into three broad categories 1) expensive, efficient monocrystalline silicon, 2) less efficient but much lower cost polycrystalline silicon, and 3) the lowest cost and poorest performer, amorphous silicon material. Conversion efficiencies of commercial polycrystaUine silicon cells are 10 to 15 percent. Now the primary development areas are in how to use monocrystalline silicon with solar concentrators and making thin-film cells by depositing a 5- to 20-micron film of silicon onto an inexpensive substrate, because the estimated efficiency of these cells is above 20 percent. Work is ongoing with other materials, including amorphous silicon (a-Si), copper indium diselenide (CuInSe2 or CIS) and related materials, and cadmium telluride (CdTe). 

Cadmium telluride is an important material for solar cells,... 

Variety of semiconducting material such as single and poly crystal silicon, amorphous silicon, Cadmium-Telluride (CdTe), Copper Indium/Gal-lium Di Selenide (CIGS) have been employed to form inorganic solar cell based on layers configuration to enhance absorption efficiency, conversion efficiency, production and maintenance cost. 

Phases formed on semiconductor surfaces can change the electrical properties in an uncontrolled, deleterious fashion. Oxide passivation layers on compound semiconductors (e.g., mercury cadmium telluride IR detectors or gallium arsenide solar cells) can be grown to impart protection to the surfaces and to stabilize electrical properties by preventing uncontrolled reactions. 

Photovoltaic (PV) Cell Semiconducting material, such as crystalline silicon or cadmium telluride, that converts solar radiation into direct current electricity using the photoelectric effect. 

Lepiller C, Cowache P, Guillemoles JF, Gibson N, Ozsan E, Lincot D (2000) Fast electrodeposition route for cadmium telluride solar cells. Thin Solid Films 361-362 118... 

Mercury cadmium telluride is used for recording thermal images in infrared cameras. The use of high-purity tellurium in cadmium teUuride solar cells is very promising, and some of the highest efficiencies for electric power generation have been obtained by using this material. 

Semiconductor deposition materials used include amorphous silicon, polycrystalline silicon, micro-crystalline silicon, cadmium telluride, and copper indium selenide/sulfide. Typically, the top surface is low iron solar glass for rigid cells (a fluoropolymer for flexible cells), the encapsulant is crosslinkable ethylene-vinyl acetate (EVA), and the rear layer is a Tedlar - PET - Tedlar laminate (although glass, coated PET, or another bondable polymeric film are also used). 

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