title: Identifying and Eliminating Emissive Sub-bandgap States in Thin Films of PbS Nanocrystals.
abstract: Chemical oxidation of under-charged Pb atoms reduces the density of trap states by a factor of 40 in films of colloidal PbS quantum dots for devices. These emissive sub-bandgap states are a byproduct of several standard ligand-exchange procedures. X-ray photoelectron spectro-scopy measurements and density function theory simulations demonstrate that they are associated with under-charged Pb.
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
authors.forename: Gyu Weon
authors.initials: GW
authors.lastname: Hwang
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
authors.forename: Donghun
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge MA, 02139, USA.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Cordero
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge MA, 02139, USA.
authors.forename: Mark W B
authors.initials: MWB
authors.lastname: Wilson
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
authors.forename: Chia-Hao M
authors.initials: CM
authors.lastname: Chuang
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Grossman
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge MA, 02139, USA.
authors.forename: Moungi G
authors.initials: MG
authors.lastname: Bawendi
keywords: lead sulfide; origin of trap states; quantum dots; sub-bandgap emission; trap density