title: Air-Stable, Near- to Mid-Infrared Emitting Solids of PbTe/CdTe Core-Shell Colloidal quantum dots.
abstract: Light emitters and detectors operating in the near- and mid-infrared spectral regions are important to many applications, such as telecommunications, high-resolution gas analysis, atmospheric pollution monitoring, medical diagnostics, and night vision. Various lead chalcogenides (binary, ternary, and quaternary alloys) in the form of quantum dots (QDs) or quantum wells provide narrow bandgap energies that cover the broad infrared region corresponding to wavelengths of 1-30 μm. Here, we report an inexpensive, all-solution-based synthesis strategy to thin-film solids consisting of 5-16 nm PbTe QDs encapsulated by CdTe shells. Colloidally synthesized PbTe QDs were first converted into core-shell PbTe/CdTe QDs, and then deposited as thin films. The subsequent fusion of the CdTe shells is achieved by ligand removal and annealing in the presence of CdCl2 . Contrary to highly unstable bare PbTe QDs, PbTe/CdTe QD solids exhibit bright and stable near- to mid-infrared emission at wavelengths of 1-3 μm, which is also retained upon prolonged storage at ambient conditions for one year.
authors.affiliation: Department of Chemistry and Applied Bioscience, ETH Zürich, 8093, Zürich, Switzerland.|Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600, Dübendorf, Switzerland.
authors.forename: Loredana
authors.initials: L
authors.lastname: Protesescu
authors.affiliation: Department of Chemistry and Applied Bioscience, ETH Zürich, 8093, Zürich, Switzerland.|Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600, Dübendorf, Switzerland.
authors.forename: Tanja
authors.initials: T
authors.lastname: Zünd
authors.affiliation: Department of Chemistry and Applied Bioscience, ETH Zürich, 8093, Zürich, Switzerland.|Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600, Dübendorf, Switzerland.
authors.forename: Maryna I
authors.initials: MI
authors.lastname: Bodnarchuk
authors.affiliation: Department of Chemistry and Applied Bioscience, ETH Zürich, 8093, Zürich, Switzerland. mvkovalenko@ethz.ch.|Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600, Dübendorf, Switzerland. mvkovalenko@ethz.ch.
authors.forename: Maksym V
authors.identifier: http://orcid.org/0000-0002-6396-8938
authors.initials: MV
authors.lastname: Kovalenko
mesh_terms: D002104:Cadmium / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry*; D007259:Infrared Rays; D007854:Lead / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D045663:Quantum Dots; D013691:Tellurium / Q000737:chemistry*
chemical_list: D003102:Colloids; D002104:Cadmium; D007854:Lead; D013691:Tellurium
keywords: colloids; core-shell nanoparticles; infrared; photoluminescence; quantum dots