title: Black silicon solar cells with interdigitated back-contacts achieve 22.1% efficiency.
abstract: The nanostructuring of silicon surfaces--known as black silicon--is a promising approach to eliminate front-surface reflection in photovoltaic devices without the need for a conventional antireflection coating. This might lead to both an increase in efficiency and a reduction in the manufacturing costs of solar cells. However, all previous attempts to integrate black silicon into solar cells have resulted in cell efficiencies well below 20% due to the increased charge carrier recombination at the nanostructured surface. Here, we show that a conformal alumina film can solve the issue of surface recombination in black silicon solar cells by providing excellent chemical and electrical passivation. We demonstrate that efficiencies above 22% can be reached, even in thick interdigitated back-contacted cells, where carrier transport is very sensitive to front surface passivation. This means that the surface recombination issue has truly been solved and black silicon solar cells have real potential for industrial production. Furthermore, we show that the use of black silicon can result in a 3% increase in daily energy production when compared with a reference cell with the same efficiency, due to its better angular acceptance.
authors.affiliation: Department of Micro and Nanosciences, Aalto University, Tietotie 3, Espoo 02150, Finland.
authors.forename: Hele
authors.initials: H
authors.lastname: Savin
authors.affiliation: Department of Micro and Nanosciences, Aalto University, Tietotie 3, Espoo 02150, Finland.
authors.forename: Päivikki
authors.initials: P
authors.lastname: Repo
authors.affiliation: Department of Micro and Nanosciences, Aalto University, Tietotie 3, Espoo 02150, Finland.
authors.forename: Guillaume
authors.initials: G
authors.lastname: von Gastrow
authors.affiliation: Departament d'Enginyeria Electrònica, Universitat Politècnica de Catalunya, Jordi Girona 1-3, Mòdul C4, Barcelona 08034, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Ortega
authors.affiliation: Departament d'Enginyeria Electrònica, Universitat Politècnica de Catalunya, Jordi Girona 1-3, Mòdul C4, Barcelona 08034, Spain.
authors.forename: Eric
authors.initials: E
authors.lastname: Calle
authors.affiliation: Departament d'Enginyeria Electrònica, Universitat Politècnica de Catalunya, Jordi Girona 1-3, Mòdul C4, Barcelona 08034, Spain.
authors.forename: Moises
authors.initials: M
authors.lastname: Garín
authors.affiliation: Departament d'Enginyeria Electrònica, Universitat Politècnica de Catalunya, Jordi Girona 1-3, Mòdul C4, Barcelona 08034, Spain.
authors.forename: Ramon
authors.initials: R
authors.lastname: Alcubilla