title: Structural, optical, and electrical properties of self-assembled films of PbSe nanocrystals treated with 1,2-ethanedithiol.
abstract: We describe the structural, optical, and electrical properties of high-quality films of PbSe nanocrystals fabricated by a layer-by-layer (LbL) dip-coating method that utilizes 1,2-ethanedithiol (EDT) as an insolubilizing agent. Comparative characterization of nanocrystal films made by spin-coating and by the LbL process shows that EDT quantitatively displaces oleic acid on the PbSe surface, causing a large volume loss that electronically couples the nanocrystals while severely degrading their positional and crystallographic order of the films. Field-effect transistors based on EDT-treated films are moderately conductive and ambipolar in the dark, becoming p-type and 30-60 times more conductive under 300 mW cm(-2) broadband illumination. The nanocrystal films oxidize rapidly in air to yield, after short air exposures, highly conductive p-type solids. The LbL process described here is a general strategy for producing uniform, conductive nanocrystal films for applications in optoelectronics and solar energy conversion.
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Luther
authors.forename: Matt
authors.initials: M
authors.lastname: Law
authors.forename: Qing
authors.initials: Q
authors.lastname: Song
authors.forename: Craig L
authors.initials: CL
authors.lastname: Perkins
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Beard
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Nozik
mesh_terms: D003460:Crystallization / Q000379:methods*; D004553:Electric Conductivity; D004563:Electrochemistry / Q000379:methods*; D007854:Lead / Q000737:chemistry*; D008027:Light; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008567:Membranes, Artificial; D008623:Mercaptoethanol / Q000031:analogs & derivatives* / Q000737:chemistry; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D010777:Photochemistry / Q000379:methods*; D012031:Refractometry; D012542:Scattering, Radiation; D018036:Selenium Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D008567:Membranes, Artificial; D018036:Selenium Compounds; C088065:lead selenide; D007854:Lead; D008623:Mercaptoethanol; C031854:1,2-ethanedithiol