Highly Emissive Colloidal CdSe/CdS Heterostructures of Mixed Dimensionality

Abstract

We demonstrate that efficient shape control may be achieved in the shell of colloidally grown semiconductor nanocrystals (independent of the core), allowing the combination of a 0-D spherical CdSe core with a 1-D rodlike CdS shell. Besides exhibiting linearly polarized emission with a room-temperature quantum efficiency above 70%, these mixed-dimensionality colloidal heterostructures display large, length-dependent Stokes shifts as well as giant extinction coefficients approaching 10 7 cm -1 M -1 .

Seeded Growth of Highly Luminescent CdSe/CdS Nanoheterostructures with Rod and Tetrapod Morphologies

“…The solution of CdSe seeds in TOP can be added to the reaction mixture either together with TOPS or 30-60s later, i.e., during the induction period. CdS easily nucleates at the surface of CdSe seeds [11,17]. We found that the structure of the CdSe seeds determined the morphology of CdSe/CdS nano-heterostructures.…”

“…In this work we compared w-CdSe and zb-CdSe nanocrystals for seeded growth of CdSe/CdS nano-hererostructures with different morphologies. Combining CdSe and CdS in a single nanostructure creates a material with heterogeneous carrier confinement or "mixed dimentionality" where holes are confined to CdSe while electrons can move freely between CdSe and CdS phases, spreading over the entire nanostructure [11,17]. Previously we synthesized structures consisting of a spherical CdSe nanocrystal connected to a CdS nanorod [17].…”

“…Our earlier studies demonstrated very efficient charge transfer from the CdS rod to the emitting CdSe core [17]. To quantify the efficiency of transfer from CdS to CdSe in heterostructures with different morphologies, we measured PL excitation (PLE) spectra.…”

Type-tunable amplified spontaneous emission from core-seeded CdSe/CdS nanorods controlled by exciton–exciton interaction

“…With advances in the colloidal synthesis of CdSe/CdS core/shell NRs, it is possible to synthesize highly efficient and crystalline CdSe/CdS core/shell NRs having a narrow size distribution by nely controlling their shape and size. 15,16 Furthermore, due to shallow band offset for electrons in the CdSe/CdS core/shell material system, a partial separation of electron and hole wavefunctions is observed which is known as the quasi type-II electronic structure that contributes to the suppression of Auger recombination, which is highly critical for achieving lasing. 11,[16][17][18] The other advantage of having a lower energy barrier for electrons in CdSe/CdS NRs is that, by simply changing their core and shell sizes, it is possible to tailor the electron and hole wavefunction overlap and tune CdSe/CdS NRs from type-I-like to quasi-type-II-like band alignment, which can be an important design consideration when engineering the gain/loss mechanisms in practical lasing systems.…”

Doping Group IIB Metal Ions into Quantum Dot Shells via the One‐Pot Decomposition of Metal‐Dithiocarbamates

“…Since then, the use of fatty acid salts of zinc and elemental sulphur have been reported, but these routes require multiple injection steps. [26,27] A more attractive approach is the use of air-stable, single-source precursors, which decompose at low temperatures, yielding the desired material. Metal dithiocarbamates represent a class of compounds which decompose to yield corresponding metal sulphides.…”