title: Perovskite energy funnels for efficient light-emitting diodes.
abstract: Organometal halide perovskites exhibit large bulk crystal domain sizes, rare traps, excellent mobilities and carriers that are free at room temperature-properties that support their excellent performance in charge-separating devices. In devices that rely on the forward injection of electrons and holes, such as light-emitting diodes (LEDs), excellent mobilities contribute to the efficient capture of non-equilibrium charge carriers by rare non-radiative centres. Moreover, the lack of bound excitons weakens the competition of desired radiative (over undesired non-radiative) recombination. Here we report a perovskite mixed material comprising a series of differently quantum-size-tuned grains that funnels photoexcitations to the lowest-bandgap light-emitter in the mixture. The materials function as charge carrier concentrators, ensuring that radiative recombination successfully outcompetes trapping and hence non-radiative recombination. We use the new material to build devices that exhibit an external quantum efficiency (EQE) of 8.8% and a radiance of 80 W sr-1m-2. These represent the brightest and most efficient solution-processed near-infrared LEDs to date.
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Mingjian
authors.initials: M
authors.lastname: Yuan
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.|Department of Chemistry and Nano Science, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Korea.
authors.forename: Li Na
authors.initials: LN
authors.lastname: Quan
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Comin
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Grant
authors.initials: G
authors.lastname: Walters
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Randy
authors.initials: R
authors.lastname: Sabatini
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, 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, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Hoogland
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.|Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4, Canada.
authors.forename: Yongbiao
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Eric M
authors.initials: EM
authors.lastname: Beauregard
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Pongsakorn
authors.identifier: 0000-0002-4854-1733
authors.initials: P
authors.lastname: Kanjanaboos
authors.affiliation: Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4, Canada.
authors.forename: Zhenghong
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Korea.
authors.forename: Dong Ha
authors.identifier: 0000-0003-0444-0479
authors.initials: DH
authors.lastname: Kim
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Sargent