title: Air-stable n-type colloidal quantum dot solids.
abstract: Colloidal quantum dots (CQDs) offer promise in flexible electronics, light sensing and energy conversion. These applications rely on rectifying junctions that require the creation of high-quality CQD solids that are controllably n-type (electron-rich) or p-type (hole-rich). Unfortunately, n-type semiconductors made using soft matter are notoriously prone to oxidation within minutes of air exposure. Here we report high-performance, air-stable n-type CQD solids. Using density functional theory we identify inorganic passivants that bind strongly to the CQD surface and repel oxidative attack. A materials processing strategy that wards off strong protic attack by polar solvents enabled the synthesis of an air-stable n-type PbS CQD solid. This material was used to build an air-processed inverted quantum junction device, which shows the highest current density from any CQD solar cell and a solar power conversion efficiency as high as 8%. We also feature the n-type CQD solid in the rapid, sensitive, and specific detection of atmospheric NO2. This work paves the way for new families of electronic devices that leverage air-stable quantum-tuned materials.
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Ning
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: Division of Physical Sciences and Engineering, Solar and Photovoltaics Engineering Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Jun
authors.initials: J
authors.lastname: Pan
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: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Valerio
authors.initials: V
authors.lastname: Adinolfi
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Jixian
authors.initials: J
authors.lastname: Xu
authors.affiliation: School of Optical and Electronic Information, Huazhong University of Science and Technology, 1037 Luoyu Road Wuhan, Hubei 430074, China.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.affiliation: Division of Physical Sciences and Engineering, Solar and Photovoltaics Engineering Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Ahmad R
authors.initials: AR
authors.lastname: Kirmani
authors.affiliation: Dalhousie University, Department of Physics and Atmospheric Science, Rm 319 Dunn Building Halifax, Nova Scotia, B3H 4R2, Canada.
authors.forename: Jon-Paul
authors.initials: JP
authors.lastname: Sun
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road Toronto, Ontario, M5S 3G4, Canada.
authors.forename: James
authors.initials: J
authors.lastname: Minor
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Kyle W
authors.initials: KW
authors.lastname: Kemp
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Haopeng
authors.initials: H
authors.lastname: Dong
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Lisa
authors.initials: L
authors.lastname: Rollny
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road Toronto, Ontario, M5S 3G4, Canada.
authors.forename: André
authors.initials: A
authors.lastname: Labelle
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Graham
authors.initials: G
authors.lastname: Carey
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road Toronto, Ontario, M5S 3G4, Canada.
authors.forename: Brandon
authors.initials: B
authors.lastname: Sutherland
authors.affiliation: Dalhousie University, Department of Physics and Atmospheric Science, Rm 319 Dunn Building Halifax, Nova Scotia, B3H 4R2, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: Hill
authors.affiliation: Division of Physical Sciences and Engineering, Solar and Photovoltaics Engineering Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Aram
authors.initials: A
authors.lastname: Amassian
authors.affiliation: School of Optical and Electronic Information, Huazhong University of Science and Technology, 1037 Luoyu Road Wuhan, Hubei 430074, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Liu
authors.affiliation: Wuhan National Laboratory for Optoelectronics, Huazhong University of Sciences and Technology, 1037 Luoyu Road Wuhan, Hubei 430074, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Tang
authors.affiliation: Division of Physical Sciences and Engineering, Solar and Photovoltaics Engineering Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Osman M
authors.initials: OM
authors.lastname: Bakr
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