- Thin-film silicon solar panels on rooftop
- Schematic structures of crystalline silicon, amorphous silicon, and amorphous hydrogenated silicon
- Solar calculator with amorphous solar cell (upper right corner) and LCDs.
Amorphous silicon (a-Si) is the non-crystalline form of silicon used for solar cells and thin-film transistors in LCDs.
Used as semiconductor material for a-Si solar cells, or thin-film silicon solar cells, it is deposited in thin films onto a variety of flexible substrates, such as glass, metal and plastic. Amorphous silicon cells generally feature low efficiency.
As a second-generation thin-film solar cell technology, amorphous silicon was once expected to become a major contributor in the fast-growing worldwide photovoltaic market, but has since lost its significance due to strong competition from conventional crystalline silicon cells and other thin-film technologies such as CdTe and CIGS.[citation needed] Amorphous silicon is a preferred material for the thin film transistor (TFT) elements of liquid crystal displays (LCDs) and for x-ray imagers.
Amorphous silicon differs from other allotropic variations, such as monocrystalline silicon—a single crystal, and polycrystalline silicon, that consists of small grains, also known as crystallites.