Quantum dots with a III-V core and an alloyed II-VI external shell
AssigneeQustomDot B.V.
InventorsZeger Hens, Mickael Tessier, Dorian Dupont
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Abstract
The present disclosure relates to quantum dots with a core of III-V material, a first layer of II-VI material and an external shell of II-VI material to be used, for example, in downconverters. The external shell is preferably made of an alloy of Zn and Cd with Se or S. Introducing a small amount of Cd in the external shell provides excellent absorbance performance in blue, violet and UV wavelengths. The amount of Cd needed for this increase in absorbance can be very low. Further, the emitted light can be nearly monochromatic, which is especially interesting in electronic applications.
Claims13
Quantum dot comprising:
- a core of InP;
- a first layer of ZnSe;
- and
- an external shell of a ternary or quaternary II-VI material consisting in:
- Zn,
- Cd, and
- at least one element selected from the group consisting of S and Se,
- wherein the ratio between the number of atoms of Cd and the sum of the number of atoms of Zn and the number of atoms of Cd is between 0.02 and 0.2.
A process for producing a quantum dot comprising the steps of:
- (a) producing a core nanocrystal of a binary, ternary or quaternary III-V material consisting in:
- at least one element selected from the group consisting of In, Ga and Al, and
- at least one element selected from the group consisting of P and As;
- (b) forming a first layer on the core nanocrystal, the first layer being of a binary or ternary II-VI material consisting in:
- Zn, and
- at least one element selected from the group consisting of S and Se;
- (c) forming an external shell on the first layer, the external shell being of a ternary or quaternary II-VI material consisting in:
- Zn
- Cd, and
- at least one element selected from the group consisting of S and Se;
- and
- wherein the external shell is made of an alloy of Zn, Cd and Se and step (c) comprises adding a compound including Cd, a compound including Zn and a compound including Se to a solution produced at step (b);
- and
- wherein step (c) comprises, in this order:
- adding a compound including Cd and a compound including Zn to a solution produced at step (b), and
- adding a compound including Se, and
- wherein the atomic ratio between the added Cd and the added Cd plus the added Zn is between 0.02 and 0.2.
Dependencies are inferred from the claim text.