title: Engineering metal-impurity nanodefects for low-cost solar cells.
abstract: As the demand for high-quality solar-cell feedstock exceeds supply and drives prices upwards, cheaper but dirtier alternative feedstock materials are being developed. Successful use of these alternative feedstocks requires that one rigorously control the deleterious effects of the more abundant metallic impurities. In this study, we demonstrate how metal nanodefect engineering can be used to reduce the electrical activity of metallic impurities, resulting in dramatic enhancements of performance even in heavily contaminated solar-cell material. Highly sensitive synchrotron-based measurements directly confirm that the spatial and size distributions of metal nanodefects regulate the minority-carrier diffusion length, a key parameter for determining the actual performance of solar-cell devices. By engineering the distributions of metal-impurity nanodefects in a controlled fashion, the minority-carrier diffusion length can be increased by up to a factor of four, indicating that the use of lower-quality feedstocks with proper controls may be a viable alternative to producing cost-effective solar cells.
authors.affiliation: Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
authors.forename: Tonio
authors.initials: T
authors.lastname: Buonassisi
authors.forename: Andrei A
authors.initials: AA
authors.lastname: Istratov
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Marcus
authors.forename: Barry
authors.initials: B
authors.lastname: Lai
authors.forename: Zhonghou
authors.initials: Z
authors.lastname: Cai
authors.forename: Steven M
authors.initials: SM
authors.lastname: Heald
authors.forename: Eicke R
authors.initials: ER
authors.lastname: Weber
mesh_terms: D003460:Crystallization / Q000379:methods*; D011211:Electric Power Supplies; D004867:Equipment Design / Q000379:methods; D019544:Equipment Failure Analysis; D008422:Materials Testing; D008670:Metals / Q000032:analysis / Q000737:chemistry*; D008832:Microchemistry / Q000379:methods*; D049329:Nanostructures / Q000032:analysis / Q000737:chemistry*; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D012993:Solar Energy; D013499:Surface Properties
chemical_list: D008670:Metals