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Identifying and Eliminating Emissive Sub-bandgap States in Thin Films of PbS Nanocrystals
Gyu Weon Hwang1, Donghun Kim1, Jose M Cordero2
1Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
Advanced Materials (Deerfield Beach, Fla.)
|July 3, 2015
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.

