Solar Energy Information Center

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Safety data, research and properties for AE Solar Energy™ materials are provided below. American Elements is a manufacturer and supplier specializing in materials essential to several solar energy technologies.

The history of solar energy materials began in the 1970s with the first silicon-based photovoltaic (PV) cells. These basic cells were created by doping silicon to form two oppositely charged layers. A positively charged or p-type layer underneath a negatively charged or n-type layer. In first configurations the p-type layer was doped with Boron to create the positive charge and n-type layer was doped with phosphorous.

When the sun's energy in the form of photons collects in the cell layers in a volume sufficient to force electrons in the layer materials from their "Valence Band" to their "Conduction Band", electrons from the layers are released. This energy threshold is referred to as the "Band Gap". These freed electrons naturally attempt to flow from the negatively charge N-type layer to the positively charged P-type layer. For this reason, the P-type layer is also sometimes called the "Absorption Layer" and the N-Type layer is called the "Emitter Layer".

However, the boundary between these two layers, which is called the "P-N Junction" or "Adhesion Layer" blocks their flow. Collection circuits are attached from the N-type layer to the P-type layer to allow for the electrons to reach their target and complete the circuit. Energy in the form of electricity is collected or harvested from this external circuit.

These silicon based photovoltaic cells have gone through several generations of development designed to reduce production costs. Originally the layers were produced by growing and slicing doped single crystals of silicon. To save cost producers began casting shapes using polycrystalline silicon. While less expensive to produce, efficiencies are also lower. A silicon single crystal may have as high as 30% efficiency; polycrystalline silicon might reach 10-15%. The least expensive approach but also the least efficient cell (approximately 5%) is produced through thin film deposition of amorphous silicon using sputtering techniques.

Presently, most silicon-based PV solar cells are produced from polycrystalline silicon with single crystal systems the next most common.

All silicon-based photovoltaic solar energy collectors however suffer from their ability to absorb energy from a relatively narrow range of the sun's light wave emission. Substantial research ha gone into developing materials that can either expand the band gap or create multiple band gaps in order to absorb a greater portion of the solar energy spectrum. This has lead to the development of PV cells based on Copper Indium Selenide (CuInSe2) or "CIS" Absorption Layers which can capture energy from portions of the light's spectrum not collected by silicon-based PV cells. Doping CIS with Gallium increases the band gap even further and as such most PV cells are now based on Copper Indium Gallium Selenide (CuInGaSe2) and are referred to as "CIGS".

In the typical CIGS photovoltaic cell, the CIGS layer acts as the the P-type or absorption layer. A second material, Cadmium Selenide (CdSe) functions as the emitter or N-type layer. Because two different materials are uses these are sometimes referred to as "Heterojunction" systems. The external circuit is provided by a zinc oxide contact layer on the N-Type layer and a Molybdenum metal contact layer on the P-Type layer.

CIGS based solar cells are a rapidly growing segment of the solar energy market. Besides being more efficient that silicon-based solar cells and therefore less expensive per watt of energy generated, they can be designed to bend to complex geometries and are very light weight. Due to their high efficiency, layers can be achieved using thin film techniques. Thin film deposition of Silicon Nanoparticle quantum dots on the polycrystalline silicon substrate of a photovoltaic (solar) cell increases voltage output as much as 60% by fluorescing the incoming light prior to capture.

Other promising designs include cells based on III-IV Nitride materials and research on Zinc Manganese Telluride, Cadmium Telluride (CdTe) and Gallium Selenide P-Type layers.

The band gap for III-IV Nitride materials, such as Gallium Indium Nitride, covers nearly the entire energy spectrum of the sun because of multiple band gaps in the semiconductor materials. Similarly, Zinc Manganese Telluride crystals have three band gaps which can absorb greater than 50% of the solar energy spectrum.

Further important research involves nanotechnology approaches using nanoparticles of the above materials. Below please find further technical and safety information on solar energy materials manufactured by American Elements' AE Solar EnergyT group.

Silicon-Based PV Cells (P and N Type)	CIS and CIGS-Based PV Cells	Other PV Cell Technologies
Single Crystal Silicon Ingot	Copper Indium Selenide Single Crystal	Zinc Manganese Telluride
Polycrystalline Silicon Powder	Copper Indium Selenide Powder	Cadmium Telluride
Amorphous Silicon Powder	Copper Indium Selenide Sputtering Target	Gallium Selenide Single Crystal
Silicon Sputtering Target	Copper Indium Selenide Nanoparticles	Gallium Selenide Sputtering Target
Silicon Rod	Copper Indium Gallium Selenide Single Crystal	Gallium Arsenide
Silicon Pellets	Copper Indium Gallium Selenide Powder
Silicon Nanoparticles	Copper Indium Gallium Selenide Nanoparticles
	Copper Selenide Sputtering Target
	Indium Selenide Sputtering Target
	Copper Gallium Selenide Sputtering Target
	Molybdenum Sputtering Target
	Zinc Oxide Sputtering Target
	Zinc Oxide Nanopowder, Z-MiteT

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