PP1.1 Solar Silicon
The use of lower cost silicon feedstocks is considered one of the likely routes for significant further cost reductions for silicon photovoltaics. Indeed, recent research raises the prospect of using solar-grade feedstocks with less than one fifth the embodied energy and half the price of conventional electronic-grade silicon, while still achieving cell efficiencies above 20%. Especially promising is the use of low-cost n-type feedstocks, with the attendant advantages of its relative immunity to common metal impurities. However, such advances require an in-depth understanding of the dominant defects and impurities in such materials, including the development of sensitive methods to detect them. Such capabilities allow the development of strategies and processes to eliminate or reduce their impact. ANU has an international reputation in this field with UNSW recently developing new hydrogenation approaches that will also be relevant. Building on this foundation, in this Program Package (PP1.1), we have demonstrated cell efficiencies of 19% using wafers sourced from 100% solar-grade silicon within the first 4 years. Beyond that, we aim to use solar-grade silicon wafers for rear-junction n-type solar cells with efficiencies of 23%, similar to the best cells available today using conventional silicon, or to reach similar efficiencies with such materials by alternative approaches.