Energy Transfer and Polarized Emission in Cadmium Selenide Nanocrystal Solids with Mixed Dimensionality

Abstract

Excited‐state energy transfer from spherical green‐light‐emitting nanocrystals as donor to rod‐shaped red‐light‐emitting nanocrystals as acceptor results in red fluorescence in mixed films. Uniaxial alignment of the quantum rods provides polarized emission, while the absorption remains unpolarized (see figure).

Formation of nanoscale spatially indirect excitons: Evolution of the type-II optical character of CdTe/CdSe heteronanocrystals

“…The 1͚ 1/2͑h͒ → 1͚ e and 1͟ 1/2͑h͒ → 1͟ e transitions of CdSe nanorods with 2.9 nm diameter and 10.5 nm length have been observed at 2.2 eV and 2.65 eV, respectively. 27 The blueshift expected for nanorods with 2.9 nm diameter and 4 nm length is only 0.05 eV, 36 placing these transitions at 2.25 and 2.70 eV. These energies are considerably lower than the peak positions observed for sample 55%CdSe, suggesting that other indirect exciton transitions are also contributing to the PLE spectra of the type-II CdTe/CdSe heteroNCs investigated here ͓Figs.…”

Unusual Fluorescent Properties of Stilbene Units and CdZnS/ZnS Quantum Dots Nanocomposites: White‐Light Emission in Solution versus Light‐Harvesting in Films

“…It was thus assumed that the shortening of lifetime of donor was dominated by FRET process. For both pure donor and blended system, the fluorescence emission decayed in a multiexponential manner, which meant the energy transfer occurred with different rate constants due to the inhomogeneous nature of films (slightly different aggregation in different domain of films) . The absorption of donors would contribute to the energy transfer induced fluorescence enhancement of acceptor, which can be reflected in the excitation spectra of the donor, acceptor and blend system, as indicated in Figure d.…”

Optical Spectroscopy of Dark and Bright Excitons in CdSe Nanocrystals in High Magnetic Fields

“…They were fabricated following a standard procedure described in ref . All investigated samples were extensively characterized by transmission electron microscopy (TEM) and optical spectroscopy as reported in refs , , and . Representative TEM images for some of the investigated nearly spherical CdSe NCs are shown as Supporting Information.…”

“…An extra set of type-I CdSe QD samples with a thin CdS–shell inorganic capping was also used with core size R = 1.75 nm and three monolayers of CdS shell. They were fabricated following a standard procedure described in ref . All investigated samples were extensively characterized by transmission electron microscopy (TEM) and optical spectroscopy as reported in refs , , and .…”

“…An extra set of type-I CdSe QD samples with a thin CdS−shell inorganic capping was also used with core size R = 1.75 nm and three monolayers of CdS shell. They were fabricated following a standard procedure described in ref 30 5(a). The PL full-width at halfmaximum (fwhm) is ∼100 meV and agrees well with the inhomogeneous broadening due to the size dispersion within our QD ensemble samples.…”