title: Colloidal-quantum-dot photovoltaics using atomic-ligand passivation.
abstract: Colloidal-quantum-dot (CQD) optoelectronics offer a compelling combination of solution processing and spectral tunability through quantum size effects. So far, CQD solar cells have relied on the use of organic ligands to passivate the surface of the semiconductor nanoparticles. Although inorganic metal chalcogenide ligands have led to record electronic transport parameters in CQD films, no photovoltaic device has been reported based on such compounds. Here we establish an atomic ligand strategy that makes use of monovalent halide anions to enhance electronic transport and successfully passivate surface defects in PbS CQD films. Both time-resolved infrared spectroscopy and transient device characterization indicate that the scheme leads to a shallower trap state distribution than the best organic ligands. Solar cells fabricated following this strategy show up to 6% solar AM1.5G power-conversion efficiency. The CQD films are deposited at room temperature and under ambient atmosphere, rendering the process amenable to low-cost, roll-by-roll fabrication.
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
authors.forename: Jiang
authors.initials: J
authors.lastname: Tang
authors.forename: Kyle W
authors.initials: KW
authors.lastname: Kemp
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Hoogland
authors.forename: Kwang S
authors.initials: KS
authors.lastname: Jeong
authors.forename: Huan
authors.initials: H
authors.lastname: Liu
authors.forename: Larissa
authors.initials: L
authors.lastname: Levina
authors.forename: Melissa
authors.initials: M
authors.lastname: Furukawa
authors.forename: Xihua
authors.initials: X
authors.lastname: Wang
authors.forename: Ratan
authors.initials: R
authors.lastname: Debnath
authors.forename: Dongkyu
authors.initials: D
authors.lastname: Cha
authors.forename: Kang Wei
authors.initials: KW
authors.lastname: Chou
authors.forename: Armin
authors.initials: A
authors.lastname: Fischer
authors.forename: Aram
authors.initials: A
authors.lastname: Amassian
authors.forename: John B
authors.initials: JB
authors.lastname: Asbury
authors.forename: Edward H
authors.initials: EH
authors.lastname: Sargent