Amorphous Silicon (a-Si) Photovoltaic

Hydrogenated amorphous silicon (a-Si:H, abbreviated to a-Si) is the most well-developed thin film photovoltaic (PV) technology. Atoms of a-Si form a continuous random network without crystalline structure over large range and dangling bonds exists due to this disorder nature. Hydrogen passivation significantly reduces the defect density of dangling bond and leads to superior electro-optical properties. The selection rules that weaken absorption in crystalline silicon (abbreviated to c-Si) do not apply to a-Si because it is amorphous. Therefore its light absorption capability is 500 times greater than c-Si. Only very thin a-Si layers in p-i-n sequence are required as active layer (~300 nm).

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