title: Pure Cubic-Phase Hybrid Iodobismuthates AgBi2 I7 for Thin-Film Photovoltaics.
abstract: Bismuth-based hybrid perovskites are candidates for lead-free and air-stable photovoltaics, but poor surface morphologies and a high band-gap energy have previously limited these hybrid perovskites. A new materials processing strategy to produce enhanced bismuth-based thin-film photovoltaic absorbers by incorporation of monovalent silver cations into iodobismuthates is presented. Solution-processed AgBi2 I7 thin films are prepared by spin-coating silver and bismuth precursors dissolved in n-butylamine and annealing under an N2 atmosphere. X-ray diffraction analysis reveals the pure cubic structure (Fd3m) with lattice parameters of a=b=c=12.223 Å. The resultant AgBi2 I7 thin films exhibit dense and pinhole-free surface morphologies with grains ranging in size from 200-800 nm and a low band gap of 1.87 eV suitable for photovoltaic applications. Initial studies produce solar power conversion efficiencies of 1.22 % and excellent stability over at least 10 days under ambient conditions.
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Younghoon
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Ankit
authors.initials: A
authors.lastname: Jain
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Voznyy
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Gi-Hwan
authors.initials: GH
authors.lastname: Kim
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Li Na
authors.initials: LN
authors.lastname: Quan
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
authors.forename: F Pelayo
authors.initials: FP
authors.lastname: García de Arquer
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Comin
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada.
authors.forename: James Z
authors.initials: JZ
authors.lastname: Fan
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada. ted.sargent@utoronto.ca.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Sargent
keywords: AgBi2I7; iodobismuthates; non-toxic photovoltaics; solution processing; thin films