title: Suppressed blinking and auger recombination in near-infrared type-II InP/CdS nanocrystal quantum dots.
abstract: Nonblinking excitonic emission from near-infrared and type-II nanocrystal quantum dots (NQDs) is reported for the first time. To realize this unusual degree of stability at the single-dot level, novel InP/CdS core/shell NQDs were synthesized for a range of shell thicknesses (~1-11 monolayers of CdS). Ensemble spectroscopy measurements (photoluminescence peak position and radiative lifetimes) and electronic structure calculations established the transition from type-I to type-II band alignment in these heterostructured NQDs. More significantly, single-NQD studies revealed clear evidence for blinking suppression that was not strongly shell-thickness dependent, while photobleaching and biexciton lifetimes trended explicitly with extent of shelling. Specifically, very long biexciton lifetimes-up to >7 ns-were obtained for the thickest-shell structures, indicating dramatic suppression of nonradiative Auger recombination. This new system demonstrates that electronic structure and shell thickness can be employed together to effect control over key single-dot and ensemble NQD photophysical properties.
authors.affiliation: Materials Physics & Applications Division: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Allison M
authors.initials: AM
authors.lastname: Dennis
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Mangum
authors.forename: Andrei
authors.initials: A
authors.lastname: Piryatinski
authors.forename: Young-Shin
authors.initials: YS
authors.lastname: Park
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Hannah
authors.forename: Joanna L
authors.initials: JL
authors.lastname: Casson
authors.forename: Darrick J
authors.initials: DJ
authors.lastname: Williams
authors.forename: Richard D
authors.initials: RD
authors.lastname: Schaller
authors.forename: Han
authors.initials: H
authors.lastname: Htoon
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Hollingsworth
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D004581:Electronics; D004583:Electrons; D007204:Indium / Q000737:chemistry; D046529:Microscopy, Electron, Transmission / Q000379:methods; D053758:Nanoparticles; D036103:Nanotechnology / Q000379:methods; D010165:Palladium / Q000737:chemistry; D010316:Particle Size; D010710:Phosphates / Q000737:chemistry; D010777:Photochemistry / Q000379:methods; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence / Q000379:methods; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013440:Sulfides / Q000737:chemistry; D013696:Temperature; D013997:Time Factors
chemical_list: D019187:Cadmium Compounds; D010710:Phosphates; D013440:Sulfides; D007204:Indium; C034939:cadmium sulfide; D010165:Palladium