Advances in amorphous silicon alloy technology—the achievement of high-efficiency multijunction solar cells and modules

Abstract

Thin-film amorphous silicon alloy technology has emerged as a strong contender for providing low-cost photovoltaic products to meet the energy needs of the 21st century. World record 14·6% initial and 13·0% stable active-area conversion efficiencies have been achieved for small-area solar cells in our laboratory using a spectral-splitting, triple-junction structure. This 0·25-cm2 device exhibited a total-area efficiency of 12·0%, as confirmed by the National Renewable Energy Laboratory. Key factors leading to this achievement will be discussed. We have also demonstrated a 10·2% stable module efficiency for a one-square-foot area. A state-of-the-art, continuous roll-to-roll production line with an annual capacity of 5 MW has been built and started production. Building-integrated photovoltaic applications are being demonstrated worldwide. Public awareness of environmental and ecological issues has provided a great opportunity for the maturing thin-film amorphous silicon alloy technology to demonstrate its viability as a major alternate energy source. © 1998 John Wiley & Sons, Ltd.