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Results on NQDs

Results from Forschungszentrum Jülich:

Jülich 1_klein Jülich 2_klein

 



The absorption cross section as well as the luminescence spectrum for the ground state transition of an ensemble of PbSe/PbS core-shell quantum dots with realistic size distribution and under resonant NIR excitation were computed based on a k∙p model for the electronic structure and a steady-state quantum-kinetic theory for the radiative rates (Phys.Chem. Chem. Phys., accepted, DOI:10.1039/C2CP42213A).

 

Results from Technion – Israel Institute of Technology:

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Absorption spectra of exemplary colloidal PbSe-QD samples. All samples obtained at reaction yields above 80 %. Size control achieved by varying the reaction conditions.

 













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TEM images of PbSe-QDs with diameters of ~ 2.5 nm, 5 nm and 6.5 nm (from left to right)

 

The size control of semiconductor quantum dots is a key issue for their application. Usually size control is achieved by the reaction time, causing in intrinsic drawback, namely that smaller sized QDs can be only prepared on the expense of reaction yield. To overcome this drawback, the concept of “size control by rate control” was recently established in II-VI QD synthesis, what focuses on the control of the nucleation rate by varying the precursor concentration. However, since this concept was not proven yet on the example of other materials, still there is doubt on its general applicability.

In the the framework of the Nanospec project we extend this concept on the synthesis of IV-VI QDs, namely on PbSe. The result is presented here (figures):

We were able to tune the first electronic transition of samples, which were all gained at reaction yields close to unity, between 1050 and 2000 nm.

This synthetic concept we from the Technion use as starting point for the syntheses of PbSe/PbS-QD to support our partners in the Nanospec project, being able to deliver this material on the gram scale.

 

Publications on NQDs

 

Anomalous Independence of Multiple Exciton Generation on Different Group IV-VI Quantum Dot Architectures (Nano Letters)

Two-Fold Emission From the S-Shell of PbSe/CdSe Core/Shell Quantum Dots (Small)


Funding

The Nanospec Project is funded by the European Community's Seventh Framework Program (FP7/2007-2013) under grant agreement no. [246200].

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