1. Amorphous silicon (a-Si) AKA Thin Film Jenny Gould and Alec Stall

2. What is amorphous silicon (a-Si)? A semiconductor material only a few micrometers thick, attached to an inexpensive backing such as glass, flexible plastic, or stainless steel. Amorphous solids, like common glass, are materials in which the atoms are not arranged in any particular order. They do not form crystalline structures at all, and they contain large numbers of structural and bonding defects.

3. Pros and Cons Low cost Amorphous silicon absorbs solar radiation 40 times more efficiently than does single- crystal silicon, so a film only about 1 micron (one one- millionth of a meter) thick can absorb 90% of the usable solar energy Can be produced at a lower temperature and can be deposited on low-cost substrates Amorphous silicon has no crystal structure and is gradually degraded by exposure to light through the Staebler-Wronski Effect. Combined with some start-up problems with encapsulation and quality control, the poor outdoor performance of a-Si products has, until recently, defined the reputation of thin films.

4. Cost comparison ManufacturerPanelOutput$/Watt KanekaK 5858 Watts$3.26/w Sanyo (amorphous and crystalline combined) HIT 167167 Watts$6.8/w UniSolarUS 6464 Watts$6.3/w Shell SolarST 4040 Watts$7.5/w