While a-Si suffers from lower electronic performance compared to c-Si, it is much more flexible in its applications. For example, a-Si layers can be made thinner than c-Si, which may produce savings on silicon material cost. One further advantage is that a-Si can be deposited at very low temperatures, e.g., as low as 75 degrees Celsius. This allows deposition on not only glass, b.
At its core, the amorphous silicon solar cell structure comprises of a thin layer of non-crystalline silicon. This thin film is typically deposited onto a substrate, creating a flexible and lightweight structure. The absence of a crystal lattice in amorphous silicon allows for a more straightforward manufacturing process and reduces material waste.
Can amorphous silicon solar cells produce low cost electricity?
The efficiency of amorphous silicon solar cells has a theoretical limit of about 15% and realized efficiencies are now up around 6 or 7%. If efficiencies of 10% can be reached on large area thin film amorphous silicon cells on inexpensive substrates, then this would be the best approach to produce low cost electricity.
The overall efficiency of this new type of solar cell was 7.1–7.9% (under simulated solar light), which is comparable to that of amorphous silicon solar cells .
How amorphous silicon photovoltaic cells are made?
The manufacture of amorphous silicon photovoltaic cells is based on plasma-enhanced chemical vapor deposition (PECVD), which can be used to produce silicon thin film. Substrate can be made of the flexible and inexpensive material in larger sizes, for example stainless steel or plastic materials. The process is the roll-to-roll method.
Instead, amorphous silicon cells use pin structures, where the i-layer is effectively undoped and provides an extended electric field between the p-i and i-n junctions. Long periods of illumination increase the dark current in these devices, as additional defects are generated.
Why do amorphous solar cells have a higher absorption than crystalline solar cells?
The amorphous silicon solar cell has a much higher absorption compared to the crystalline silicon solar cell because of its disorder in the atomic structure. The optical transitions are perceived as localized transitions, thus increasing the efficiency for optical transitions.