Thin-film solar cells made from amorphous silicon

The possibilities for a widespread use of solar cells are determined to a large degree by cost considerations. The price of commercially available solar cells is currently too high by a factor of 10 for applications in which solar cells would have to compete with conventional electric power sources. One of several approaches presently pursued to achieve the required reduction in the cost of solar cells is related to the development of thin-film solar cells. A thin-film solar cell is characterized by a light-absorbing semiconductor layer with a thickness not exceeding a few microns. In certain respects, thin-film solar cells based on the utilization of hydrogenized, amorphous silicon (a-Si:H) are currently more advanced than thin-film solar cells employing other materials. The production of a-Si:H involves the decomposition of SiH4 by means of a glow discharge. Attention is given to the significance and determination of the density of states in a-Si:H, the diffusion length, operational efficiency, cell stability, and development trends.