Publications

2003
Oded Millo, David Katz, Dov Steiner, Eli Rothenberg, Taleb Mokari, Miri Kazes, and Uri Banin. 2003. “Charging and quantum size effects in tunnelling and optical spectroscopy of CdSe nanorods.” Nanotechnology, 15, 1, Pp. R1. Publisher's Version Abstract

We summarize our correlated scanning tunnelling microscopy and optical spectroscopy investigations of the electronic level structure and single-electron charging effects in CdSe quantum rods. Both optical and tunnelling spectra show that the level structure depends primarily on rod diameter and not on length. With increasing diameter, the bandgap and the excited state level spacings shift to the red. The level structure is assigned using a multi-band effective-mass model. The tunnelling spectra also exhibit, depending on the tunnel-junction parameters, single-electron charging effects that yield information on the degeneracy of the electronic states.

Fernando Patolsky, Ron Gill, Yossi Weizmann, Taleb Mokari, Uri Banin, and Itamar Willner. 2003. “Lighting-up the dynamics of telomerization and DNA replication by CdSe− ZnS quantum dots.” Journal of the American Chemical Society, 125, 46, Pp. 13918-13919. Publisher's Version Abstract

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CdSe−ZnS core−shell quantum dots (QDs) act as photochemical centers for lighting-up the dynamics of telomerization or DNA replication.

Taleb Mokari and Uri Banin. 2003. “Synthesis and properties of CdSe/ZnS core/shell nanorods.” Chemistry of materials, 15, 20, Pp. 3955-3960. Publisher's Version Abstract

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A method for the synthesis of CdSe/ZnS core/shell nanorods is reported. In the first step rods are grown, and in a second step a shell of ZnS is overgrown at moderate temperatures in a mixture of trioctylphosphine-oxide and hexadecylamine. Structural and chemical characterization using transmission electron microscopy, X-ray diffraction, and energy dispersive X-ray spectroscopy were performed providing direct evidence for shell growth. The emission quantum yield significantly increases by over 1 order of magnitude for the core/shell nanorods compared to the original rods because of the improved surface passivation. Rods with lengths up to ∼30 nm were investigated, and in this size regime the maximal achievable QY showed little dependence on length and strong dependence on rod diameter, with increased QY in smaller diameters. Color tunability is available via tuning of the rod diameter. The stability against photooxidation was significantly improved in core/shell nanorods compared with rods coated by organic ligands.

ShiHai Kan, Taleb Mokari, Eli Rothenberg, and Uri Banin. 2003. “Synthesis and size-dependent properties of zinc-blende semiconductor quantum rods.” Nature materials, 2, 3, Pp. 155-158. Publisher's Version Abstract

Dimensionality and size are two factors that govern the properties of semiconductor nanostructures1,2. In nanocrystals, dimensionality is manifested by the control of shape, which presents a key challenge for synthesis3,4,5. So far, the growth of rod-shaped nanocrystals using a surfactant-controlled growth mode, has been limited to semiconductors with wurtzite crystal structures, such as CdSe (ref. 3). Here, we report on a general method for the growth of soluble nanorods applied to semiconductors with the zinc-blende cubic lattice structure. InAs quantum rods with controlled lengths and diameters were synthesized using the solution–liquid–solid mechanism6 with gold nanocrystals as catalysts7. This provides an unexpected link between two successful strategies for growing high-quality nanomaterials, the vapour–liquid–solid approach for growing nanowires8,9,10,11,12, and the colloidal approach for synthesizing soluble nanocrystals13,14,15. The rods exhibit both length- and shape-dependent optical properties, manifested in a red-shift of the bandgap with increased length, and in the observation of polarized emission covering the near-infrared spectral range relevant for telecommunications devices16,17.

ShiHai Kan, Taleb Mokari, Eli Rothenberg, and Uri Banin. 2003. “Synthesis and size-dependent properties of zinc-blende semiconductor quantum rods.” Nature materials, 2, 3, Pp. 155. Publisher's Version Abstract

Dimensionality and size are two factors that govern the properties of semiconductor nanostructures1,2. In nanocrystals, dimensionality is manifested by the control of shape, which presents a key challenge for synthesis3,4,5. So far, the growth of rod-shaped nanocrystals using a surfactant-controlled growth mode, has been limited to semiconductors with wurtzite crystal structures, such as CdSe (ref. 3). Here, we report on a general method for the growth of soluble nanorods applied to semiconductors with the zinc-blende cubic lattice structure. InAs quantum rods with controlled lengths and diameters were synthesized using the solution–liquid–solid mechanism6 with gold nanocrystals as catalysts7. This provides an unexpected link between two successful strategies for growing high-quality nanomaterials, the vapour–liquid–solid approach for growing nanowires8,9,10,11,12, and the colloidal approach for synthesizing soluble nanocrystals13,14,15. The rods exhibit both length- and shape-dependent optical properties, manifested in a red-shift of the bandgap with increased length, and in the observation of polarized emission covering the near-infrared spectral range relevant for telecommunications devices16,17.