title: Probing charge transfer in a novel class of luminescent perovskite-based heterostructures composed of quantum dots bound to RE-activated CaTiO3 phosphors.
abstract: We report on the synthesis and structural characterization of novel semiconducting heterostructures composed of cadmium selenide (CdSe) quantum dots (QDs) attached onto the surfaces of novel high-surface area, porous rare-earth-ion doped alkaline earth titanate micron-scale spherical motifs, i.e. both Eu-doped and Pr-doped CaTiO3, composed of constituent, component nanoparticles. These unique metal oxide perovskite building blocks were created by a multi-pronged synthetic strategy involving molten salt and hydrothermal protocols. Subsequently, optical characterization of these heterostructures indicated a clear behavioral dependence of charge transfer in these systems upon a number of parameters such as the nature of the dopant, the reaction temperature, and particle size. Specifically, 2.7 nm diameter ligand-functionalized CdSe QDs were anchored onto sub-micron sized CaTiO3-based spherical assemblies, prepared by molten salt protocols. We found that both the Pr- and Eu-doped CaTiO3 displayed pronounced PL emissions, with maximum intensities observed using optimized lanthanide concentrations of 0.2 mol% and 6 mol%, respectively. Analogous experiments were performed on Eu-doped BaTiO3 and SrTiO3 motifs, but CaTiO3 still performed as the most effective host material amongst the three perovskite systems tested. Moreover, the ligand-capped CdSe QD-doped CaTiO3 heterostructures exhibited effective charge transfer between the two individual constituent nanoscale components, an assertion corroborated by the corresponding quenching of their measured PL signals.
authors.affiliation: Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400, USA. Stanislaus.wong@stonybrook.edu sswong@bnl.gov.
authors.forename: Crystal S
authors.initials: CS
authors.lastname: Lewis
authors.affiliation: Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400, USA. Stanislaus.wong@stonybrook.edu sswong@bnl.gov.
authors.forename: Haiqing
authors.initials: H
authors.lastname: Liu
authors.affiliation: Condensed Matter of Physics and Materials Sciences Department, Brookhaven National Laboratory, Building 480, Upton, NY 11973, USA.
authors.forename: Jinkyu
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400, USA. Stanislaus.wong@stonybrook.edu sswong@bnl.gov.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400, USA. Stanislaus.wong@stonybrook.edu sswong@bnl.gov.
authors.forename: Shiyu
authors.initials: S
authors.lastname: Yue
authors.affiliation: Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400, USA. Stanislaus.wong@stonybrook.edu sswong@bnl.gov.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Brennan
authors.affiliation: Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400, USA. Stanislaus.wong@stonybrook.edu sswong@bnl.gov and Condensed Matter of Physics and Materials Sciences Department, Brookhaven National Laboratory, Building 480, Upton, NY 11973, USA.
authors.forename: Stanislaus S
authors.initials: SS
authors.lastname: Wong