What Are Devices That Use Semiconductors to Produce Electricity From Solar Energy?
- Silicon wafers can be used to make computer chips or to make photovoltaic panels.Justin Sullivan/Getty Images News/Getty Images
The most common mineral element on Earth is silicon. The most common semiconductor material is also silicon. Silicon PV is not constructed from pure silicon, but silicon crystals that have been "doped" with impurities that disturb the balance of electrons in the material. The disturbed balance creates a situation where sunlight can be absorbed. The best absorption comes from monocrystalline silicon cells, constructed out of disks that are all cut from a single crystalline ingot. Amorphous silicon crystals are built from wafers that have many small crystals fabricated next to each other in a single disk. - Thin-film photovoltaic semiconductors can be built on flexible substrates.John Moore/Getty Images News/Getty Images
Monocrystalline or amorphous silicon cells are a few hundred micrometers thick, that's a few tenths of a millimeter. Thin film solar cells are only a few micrometers (a few millionths of a meter) thick. It's possible to make thin film cells from silicon, but they are not very efficient. A different semiconductor material, cadmium telluride (CdTe), works much better as a thin film photovoltaic material. Thin film CdTe panels can be built from start to finish in just a few hours, which makes them relatively inexpensive. - Another thin film technology is built from a different semiconductor: copper indium gallium selenide (CIGS). CIGS technology is not as far advanced as the other options, but it does have higher efficiency than other thin films. And the relatively high efficiency they already have is just the start --- they have the potential to reach much higher efficiency.
- Solar cells of each of the other types are built from a single semiconductor junction. The junction is the border between two slightly different semiconductor materials. The semiconductor absorbs light in an energy range determined by the two neighboring semiconductor materials. Multijunction cells are built by layering several semiconductor junctions on top of each other. Because each layer absorbs a given range of wavelengths, putting extra layers together helps the PV cell absorb far more sunlight than single-junction cells. Multijunction cells can be fabricated from several different types of semiconductor materials.
