title: Design of Heterogeneous Chalcogenide Nanostructures with Pressure-Tunable Gaps and without Electronic Trap States.
abstract: Heterogeneous nanostructures, such as quantum dots (QDs) embedded in solid matrices or core-shell nanoparticles, are promising platforms for a wide variety of applications, including phosphors with increased quantum yield, photocatalysis, and solar energy conversion. However, characterizing and controlling their interfacial morphology and defects, which greatly influence their electronic properties, have proven difficult in numerous cases. Here we carried out atomistic calculations on chalcogenide nanostructured materials, i.e., PbSe QDs in CdSe matrices and CdSe embedded in PbSe, and we established how interfacial and core structures affect their electronic properties. In particular, we showed that defects present at interfaces of PbSe nanoparticles and CdSe matrices give rise to detrimental intragap states, degrading the performance of photovoltaic devices. Instead, the electronic gaps of the inverted system (CdSe dots in PbSe) are clean, indicating that this material has superior electronic properties for solar applications. In addition, our calculations predicted that the core structure of CdSe and in turn its band gap may be tuned by applying pressure to the PbSe matrix, providing a means to engineering the properties of new functional materials.
authors.affiliation: Institute for Molecular Engineering, The University of Chicago , 5640 South Ellis Avenue, Chicago, Illinois 60637, United States.
authors.forename: Federico
authors.identifier: 0000-0003-0830-8141
authors.initials: F
authors.lastname: Giberti
authors.affiliation: Institute for Molecular Engineering, The University of Chicago , 5640 South Ellis Avenue, Chicago, Illinois 60637, United States.|Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Márton
authors.identifier: 0000-0003-1321-9207
authors.initials: M
authors.lastname: Vörös
authors.affiliation: Institute for Molecular Engineering, The University of Chicago , 5640 South Ellis Avenue, Chicago, Illinois 60637, United States.|Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Giulia
authors.initials: G
authors.lastname: Galli
keywords: Chalcogenide quantum dots; density functional theory; molecular dynamics; solar cell