# US 8,541,810 B2 · Blue light emitting semiconductor nanocrystal materials

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- Number: US 8,541,810 B2
- Document ID: US8541810B2
- Status: Granted
- Kind: B2
- Application number: 13/297,968
- Filed: 2011-11-16
- Published: 2012-03-15
- Granted: 2013-09-24
- Earliest claimed: 2004-03-08
- Assignees: Massachusettts Institute of Technology
- Applicants: Jonathan S. Steckel; John P. Zimmer; Seth Coe-Sullivan; Nathan E. Stott; Vladimir Bulović; Moungi G. Bawendi
- Inventors: Jonathan S. Steckel; John P. Zimmer; Seth Coe-Sullivan; Nathan E. Stott; Vladimir Bulović; Moungi G. Bawendi
- Web page: https://patentgrep.com/patent/US8541810B2

## CPC

- C01G 9/08: Sulfides
- B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- C01G 11/02: Sulfides
- C09K 11/02: Use of particular materials as binders, particle coatings or suspension media therefor
- C09K 11/565: {with zinc cadmium}
- H05B 33/14: characterised by the chemical or physical composition or the arrangement of the electroluminescent material {, or by the simultaneous addition of the electroluminescent material in or onto the light source}
- C01P 2004/04: obtained by TEM, STEM, STM or AFM
- C01P 2004/64: Nanometer sized, i.e. from 1-100 nanometer
- C01P 2004/84: one phase coated with the other
- C01P 2006/40: Electric properties
- H10H 20/818: within the light-emitting regions
- H10H 20/819: characterised by their shape, e.g. curved or truncated substrates
- C01G: COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts or peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium, or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds containing nitrogen, other non-metals and metal C01B21/082}; metal amides C01B21/092; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanamide C01C3/16; thiocyanates C01C3/20)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS

## Abstract

A semiconductor nanocrystal includes a core including a first semiconductor material and an overcoating including a second semiconductor material. A monodisperse population of the nanocrystals emits blue light over a narrow range of wavelengths with a high quantum efficiency.

## Claims

### Claim 1

A semiconductor nanocrystal comprising: a core including a first semiconductor material; and an overcoating on the core, the overcoating including a second semiconductor material, wherein the semiconductor nanocrystal when excited emits blue light having an intensity at least five times greater than an intensity of a deep trap emission.

### Claim 2 (depends on 1)

The nanocrystal of claim 1, wherein the nanocrystal when excited emits blue light with a quantum efficiency of at least 10%.

### Claim 3 (depends on 1)

The nanocrystal of claim 1, wherein the nanocrystal when excited emits blue light with a quantum efficiency of at least 30%.

### Claim 4 (depends on 1)

The nanocrystal of claim 1, wherein the nanocrystal when excited emits blue light with a quantum efficiency of at least 50%.

### Claim 5 (depends on 1)

The nanocrystal of claim 1, wherein the blue light has a full width at half maximum of not more than 40 nm.

### Claim 6 (depends on 1)

The nanocrystal of claim 1, wherein the blue light has a full width at half maximum of not more than 30 nm.

### Claim 7 (depends on 6)

The nanocrystal of claim 6, wherein the nanocrystal when excited emits blue light with a quantum efficiency greater than 20%.

### Claim 8 (depends on 1)

The nanocrystal of claim 1, wherein the blue light has a full width at half maximum of not more than 20 nm.

### Claim 9 (depends on 1)

The nanocrystal of claim 1, wherein the blue light has a peak wavelength shorter than 470 nm.

### Claim 10 (depends on 1)

The nanocrystal of claim 1, wherein the first semiconductor material is CdS.

### Claim 11 (depends on 10)

The nanocrystal of claim 10, wherein the second semiconductor material is ZnS.

### Claim 12 (depends on 1)

The nanocrystal of claim 1, wherein the blue light has an intensity at least ten times greater than an intensity of a deep trap emission.

### Claim 13 (depends on 1)

The nanocrystal of claim 1, wherein the blue light has an intensity at least twenty times greater than an intensity of a deep trap emission.

### Claim 14

A light emitting device comprising: a layer including a matrix; a first electrode adjacent to the layer; a second electrode opposed to the first electrode; and a plurality of semiconductor nanocrystals disposed between the first electrode and the second electrode, wherein the semiconductor when excited emit blue light having an intensity at least five times greater than an intensity of a deep trap emission.

### Claim 15 (depends on 14)

The light emitting device of claim 14, wherein the semiconductor nanocrystals include a core including a first semiconductor material and an overcoating on the core, the overcoating including a second semiconductor material.

### Claim 16 (depends on 14)

The light emitting device of claim 14, wherein the first semiconductor material is CdS.

### Claim 17 (depends on 16)

The light emitting device of claim 16, wherein the second semiconductor material is ZnS.

### Claim 18 (depends on 15)

The light emitting device of claim 15, wherein the device is capable of emitting light with a full width at half maximum of not more than 40 nm.

### Claim 19 (depends on 14)

The light emitting device of claim 14, wherein the blue light has an intensity at least ten times greater than an intensity of a deep trap emission.

### Claim 20 (depends on 14)

The light emitting device of claim 14, wherein the blue light has an intensity at least twenty times greater than an intensity of a deep trap emission.