title: Preparation of Cd/Pb Chalcogenide Heterostructured Janus Particles via Controllable Cation Exchange.
abstract: We developed a strategy for producing quasi-spherical nanocrystals of anisotropic heterostructures of Cd/Pb chalcogenides. The nanostructures are fabricated via a controlled cation exchange reaction where the Cd(2+) cation is exchanged for the Pb(2+) cation. The cation exchange reaction is thermally activated and can be controlled by adjusting the reaction temperature or time. We characterized the particles using TEM, XPS, PL, and absorption spectroscopy. With complete exchange, high quality Pb-chalcogenide quantum dots are produced. In addition to Cd(2+), we also find suitable conditions for the exchange of Zn(2+) cations for Pb(2+) cations. The cation exchange is anisotropic starting at one edge of the nanocrystals and proceeds along the ⟨111⟩ direction producing a sharp interface at a (111) crystallographic plane. Instead of spherical core/shell structures, we produced and studied quasi-spherical CdS/PbS and CdSe/PbSe Janus-type heterostructures. Nontrivial PL behavior was observed from the CdS(e)/PbS(e) heterostructures as the Pb:Cd ratio is increased.
authors.affiliation: †School of Optical and Electronic Information, Huazhong University of Science and Technology, Hubei 430074, China.|‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
authors.forename: Jianbing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: ‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
authors.forename: Boris D
authors.initials: BD
authors.lastname: Chernomordik
authors.affiliation: ‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.|§Department of Physics, Colorado School of Mines, Golden, Colorado 80401, United States.
authors.forename: Ryan W
authors.initials: RW
authors.lastname: Crisp
authors.affiliation: ‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.|∥Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Kroupa
authors.affiliation: ‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Luther
authors.affiliation: ‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
authors.forename: Elisa M
authors.initials: EM
authors.lastname: Miller
authors.affiliation: ⊥Center for Advanced Solar Photophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Gao
authors.affiliation: ‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Beard
keywords: cation-exchange reactions; heterostructures; lead chalcogenide; quantum dots; synthesis