# US 8,784,685 B2 · Core-alloyed shell semiconductor nanocrystals

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- Number: US 8,784,685 B2
- Document ID: US8784685B2
- Status: Granted
- Kind: B2
- Application number: 12/780,404
- Filed: 2010-05-14
- Published: 2011-01-13
- Granted: 2014-07-22
- Earliest claimed: 2004-09-09
- Assignees: Technion Research & Development Foundation Limited
- Applicants: Efrat Lifshitz; Ariel Kigel; Maya Brumer-Gilary; Aldona Sashchiuk; Lilac Amirav; Viktoria Kloper; Dima Cheskis; Ruth Osovsky
- Inventors: Efrat Lifshitz; Ariel Kigel; Maya Brumer-Gilary; Aldona Sashchiuk; Lilac Amirav; Viktoria Kloper; Dima Cheskis; Ruth Osovsky
- Web page: https://patentgrep.com/patent/US8784685B2

## CPC

- H10D 62/862: being Group II-VI materials comprising three or more elements, e.g. CdZnTe
- C09K 11/025: {non-luminescent particle coatings or suspension media}
- C09K 11/565: {with zinc cadmium}
- C09K 11/661: {Chalcogenides}
- C09K 11/88: containing selenium, tellurium or unspecified chalcogen elements
- C09K 11/883: {with zinc or cadmium}
- H10D 62/80: characterised by the materials
- H10D 62/874: {being Pb compounds or alloys, e.g. PbO}
- H10F 77/147: {Shapes of bodies}
- H10P 14/3402: {characterised by the chemical composition}
- H10P 14/3432: {Tellurides}
- H10P 14/3436: {being chalcogenide semiconductor materials not being oxides, e.g. ternary compounds}
- H10P 14/3461: {Nanoparticles}
- Y02E 10/50: Photovoltaic [PV] energy
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

The invention relates to a core-alloyed shell semiconductor nanocrystal comprising: (i) a core of a semiconductor material having a selected band gap energy; (ii) a core-overcoating shell consisting of one or more layers comprised of an alloy of the said semiconductor of (i) and a second semiconductor; (iii) and an outer organic ligand layer, provided that the core semiconductor material is not HgTe. In certain embodiments, the core semiconductor material is PbSe and the alloy shell semiconductor material has the PbSexS1-x structure; or the core semiconductor material is CdTe and the alloy shell semiconductor material has either the CdTexSe1-x or CdTexS1-x structure.

## Claims

### Claim 1

A core-alloyed shell semiconductor nanocrystal comprising:
(i) a core of a single semiconductor material having a selected band gap energy, said core having the structure AB;
(ii) a core-overcoating shell consisting of one or more layers comprised of an alloy of the said semiconductor of (i) and a second semiconductor, said shell having the structure ABxC1-x, wherein an interface is formed between core (i) and shell (ii); and
(iii) an outer organic ligand layer,
wherein A is Pb; B and C are different and selected from the group consisting of S, Se and Te; x is the mole fraction of B and 1−x is the mole fraction of C, with x gradually changing within a range wherein x<1 and x>0.

### Claim 2 (depends on 1)

The core-alloyed shell semiconductor nanocrystal of claim 1, wherein the band gap energy of the core semiconductor material is in the infrared energy range.

### Claim 3 (depends on 1)

The core-alloyed shell semiconductor nanocrystal of claim 1, wherein the core semiconductor material is PbSe and the alloy shell semiconductor material has the PbSexS1-x structure.

### Claim 4 (depends on 1)

The core-alloyed shell semiconductor nanocrystal of claim 1, wherein the alloyed shell exhibits gradual change of the crystallographic lattice spacing.

### Claim 5 (depends on 1)

The core-alloyed shell semiconductor nanocrystal of claim 1, wherein the alloyed shell exhibits gradual change of the dielectric constant.

### Claim 6 (depends on 1)

The core-alloyed shell semiconductor nanocrystal of claim 1, wherein the nanocrystal size is in the range of about 3 nm to about 100 nm.

### Claim 7 (depends on 1)

The core-alloyed shell semiconductor nanocrystal of claim 1, wherein said core alloyed shell semiconductor nanocrystal exhibits less than a 10% root-mean-square (rms) deviation in diameter.

### Claim 8 (depends on 1)

The core-alloyed shell semiconductor nanocrystal of claim 1, wherein the nanocrystal exhibits photoluminescence having quantum yields of greater than 20%.

### Claim 9 (depends on 1)

The core-alloyed shell semiconductor nanocrystal of claim 1, further comprising an exterior shell overcoating said alloyed shell, said exterior shell consisting of one or more layers comprised of one of said semiconductor materials.

### Claim 10 (depends on 9)

The core-alloyed shell semiconductor nanocrystal of claim 9, wherein the core has the structure of AB; the core-overcoating shell comprises an alloy of the ABxC1-x structure; and the exterior shell has the structure of AB or AC.

### Claim 11 (depends on 10)

The core-alloyed shell semiconductor nanocrystal of claim 10, wherein the core semiconductor material is PbSe or PbS, the alloy shell semiconductor material has the PbSexS1-x structure, and the exterior shell semiconductor material is PbSe or PbS.

### Claim 12 (depends on 1)

A single-pot process for the synthesis of a core-alloyed shell semiconductor nanocrystal of claim 1, comprising:
(i) simultaneous injection of stoichiometric amounts of the core and shell semiconductor precursors into a solution comprised of the organic ligands or in which solution the organic ligands are dissolved, at elevated temperatures, under inert conditions, whereby a fast nucleation of the core semiconductor material occurs, followed by a deposition of the semiconductor shell material with a gradual composition; or
(ii) injection of stoichiometric amounts of the core semiconductor precursors into a solution comprised of organic ligands or in which said organic ligands are dissolved, at elevated temperatures, under inert conditions, whereby a fast nucleation of the core semiconductor material occurs, followed by reduction of the temperature so as to terminate the core semiconductor material growth, and injection of a stoichiometric amount of the shell anionic precursor into said solution, at elevated temperatures, under inert conditions, resulting in a deposition of the semiconductor shell material with a gradual composition.

### Claim 13 (depends on 3)

A single pot process for the synthesis of a core-alloyed shell semiconductor PbSe/PbSexS1-x nanocrystal of claim 3, comprising injecting a mixture of: (i) the precursor lead acetate trihydrate, or lead oxide, dissolved in a solution of phenyl ether, oleic acid and trioctylphosphine (TOP) and (ii) a chalcogen precursor mixture of Se and S dissolved in TOP, into a pre-heated phenyl ether solution; terminating the nanocrystals growth by quenching to room temperature; and isolating the PbSe/PbSexS1-x nanocrystals.

### Claim 14 (depends on 1)

A nanocrystal array composed of a plurality of core-alloyed shell semiconductor nanocrystals of claim 1, in ordered or disordered packing, with close proximity of said nanocrystals, reserving the properties of individual nanocrystals and creating new collective effects.