title: Synthesis and spectroscopy of PbSe fused quantum-dot dimers.
abstract: We report the synthesis and characterization of Pb-chalcogenide fused quantum-dot (QD) dimer structures. The resulting QD dimers range in length from 6 to 16 nm and are produced by oriented attachment of single QD monomers with diameters of 3.1-7.8 nm. QD monomers with diameters exceeding about 5 nm appear to have the greatest affinity for QD dimer formation and, therefore, gave the greatest yields of fused structures. We find a new absorption feature in the first exciton QD dimer spectra and assign this to a splitting of the 8-fold degenerate 1S-level. The dimer splitting increases from 50 to 140 meV with decrease of the QD-monomer size, and we present a mechanism that accounts for this splitting. We also demonstrate the possibility of fusing two QDs with different sizes into a heterostructure.
authors.affiliation: National Renewable Energy Laboratory , Chemical and Material Sciences Center, Golden, Colorado 80401, United States.
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Hughes
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Blackburn
authors.forename: Daniel
authors.initials: D
authors.lastname: Kroupa
authors.forename: Andrew
authors.initials: A
authors.lastname: Shabaev
authors.forename: Steven C
authors.initials: SC
authors.lastname: Erwin
authors.forename: Alexander L
authors.initials: AL
authors.lastname: Efros
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Nozik
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Luther
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Beard