title: Hybrid organic-inorganic inks flatten the energy landscape in colloidal quantum dot solids.
abstract: Bandtail states in disordered semiconductor materials result in losses in open-circuit voltage (Voc) and inhibit carrier transport in photovoltaics. For colloidal quantum dot (CQD) films that promise low-cost, large-area, air-stable photovoltaics, bandtails are determined by CQD synthetic polydispersity and inhomogeneous aggregation during the ligand-exchange process. Here we introduce a new method for the synthesis of solution-phase ligand-exchanged CQD inks that enable a flat energy landscape and an advantageously high packing density. In the solid state, these materials exhibit a sharper bandtail and reduced energy funnelling compared with the previous best CQD thin films for photovoltaics. Consequently, we demonstrate solar cells with higher Vocand more efficient charge injection into the electron acceptor, allowing the use of a closer-to-optimum bandgap to absorb more light. These enable the fabrication of CQD solar cells made via a solution-phase ligand exchange, with a certified power conversion efficiency of 11.28%. The devices are stable when stored in air, unencapsulated, for over 1,000 h.
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada.
authors.forename: Mengxia
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: Oleksandr
authors.identifier: 0000-0002-8656-5074
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: Randy
authors.initials: R
authors.lastname: Sabatini
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: King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), and Physical Sciences and Engineering Division, 4700 KAUST, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Rahim
authors.initials: R
authors.lastname: Munir
authors.affiliation: King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), and Physical Sciences and Engineering Division, 4700 KAUST, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Ahmed Hesham
authors.initials: AH
authors.lastname: Balawi
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada.
authors.forename: Xinzheng
authors.initials: X
authors.lastname: Lan
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada.
authors.forename: Fengjia
authors.initials: F
authors.lastname: Fan
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada.
authors.forename: Grant
authors.initials: G
authors.lastname: Walters
authors.affiliation: King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), and Physical Sciences and Engineering Division, 4700 KAUST, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Ahmad R
authors.initials: AR
authors.lastname: Kirmani
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada.
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Hoogland
authors.affiliation: King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), and Physical Sciences and Engineering Division, 4700 KAUST, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Laquai
authors.affiliation: King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), and Physical Sciences and Engineering Division, 4700 KAUST, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Aram
authors.initials: A
authors.lastname: Amassian
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Sargent