Luminescent crystals and manufacturing thereof
The present invention relates to the field of luminescent crystals (LCs), and more specifically to Quantum Dots (QDs) of formula M 1 a M 2 b X c , wherein the substituents are as defined in the specification. The invention provides methods of manufacturing such luminescent crystals, particularly by dispersing suitable starting materials in the presence of a liquid and by the aid of milling balls; to compositions comprising luminescent crystals and to electronic devices, decorative coatings; and to intermediates comprising luminescent crystals.
1. A composition in the form of a suspension comprising:
(i) luminescent crystals of 2-50 nm size of formula
(I):
M 1 a M 2 b X c (I),
wherein:
M 1 represents one or more alkaline metals selected from Cs, Rb, K, Na, and Li,
M 2 represents one or more metals selected from the group consisting of Ge, Sn, Pb, Sb, and Bi,
X represents one or more halogenides selected from the group consisting of Cl, Br, and I,
a represents 1-4,
b represents 1-2,
c represents 3-9;
and
(ii) surfactant selected from the group of zwitterionic surfactants; and
(iii) optionally solvent, said solvent selected from the group of aliphatic hydrocarbons, esters, alcohols, and ketones; and
(iv) optionally polymer or pre-polymer selected from the group of acrylates, epoxies, urethanes, styrenes, and silicones and cyclic olefinic copolymers.
2. The composition according to claim 1 , wherein
the weight ratio luminescent crystals (i):liquid material (ii)+(iii)+(iv) is in the range of 0.0001-0.5; and/or
the weight ratio surfactant (ii):luminescent crystals (i) is in the range of 100-0.05; and/or
wherein the polymer or pre-polymer concentration is in the range of 0.1-30 wt %, of the total composition.
3. A composition according to claim 1 ,
wherein said zwitter-ionic surfactants comprise apolar end-groups selected from the group of alkyl or alkyl-ether chains with 4-30 carbon atoms.
4. A composition according to claim 1 ,
which is free of solvents (iii), and
wherein the weight ratio luminescent crystals (i):liquid material (pre-polymer (iv)+surfactant (ii)) is in the range of 0.0001-0.5.
5. A composition according to claim 1 ,
wherein said surfactant (ii) is a liquid surfactant and which is free of, solvents (iii) and pre-polymer (iv), and
wherein the weight ratio surfactant (ii) luminescent crystals (i) is in the range of 100-1.
6. A solid polymer composition comprising:
(ii) luminescent crystals of 2-50 nm size of formula
(I):
M 1 a M 2 b X c (I),
wherein:
M 1 represents one or more alkaline metals selected from Cs, Rb, K, Na, and Li,
M 2 represents one or more metals selected from the group consisting of Ge, Sn, Pb, Sb, and Bi,
X represents one or more halogenides selected from the group consisting of Cl, Br, and I,
a represents 1-4,
b represents 1-2,
c represents 3-9;
and
(iii) surfactant selected from the group of zwitter-ionic surfactants; and
(iv) a hardened/cured polymer.
7. The solid polymer composition according to claim 6 , wherein
the weight ratio of said luminescent crystals matrix (polymer+surfactant) is in the range of 0.0001-0.1; or
the weight ratio of said surfactant:luminescent crystals is in the range of 100-0.05.
8. The solid polymer composition of claim 6 , wherein the hardened/cured polymer is selected from the group of acrylate polymers, epoxy polymers, urethane polymers, styrene polymers, silicone polymers and cyclic olefin copolymers.
9. A composition according to claim 6 for converting blue light into white light.
10. A composition according to claim 6 for converting blue light into white light in a light emitting diode (LED) or in a liquid crystal display.
11. An intermediate good comprising a sheet-like substrate coated with one or more layers, wherein at least one of said layers is a functional layer, wherein said functional layer comprises a composition according to claim 6 .
12. An intermediate good according to claim 11 , wherein said functional layer converts blue light into white light.
13. A device, selected from the group of electronic devices and optical devices, wherein said device comprises a substrate and a functional layer; and wherein said functional layer comprises luminescent crystals of formula (I):
(I):
M 1 a M 2 b X c
wherein:
M 1 represents one or more alkaline metals selected from Cs, Rb, K, Na, and Li,
M 2 represents one or more metals selected from the group consisting of Ge, Sn, Pb, Sb, and Bi,
X represents one or more halogenides selected from the group consisting of Cl, Br, and I,
a represents 1-4,
b represents 1-2,
c represents 3-9;
and surfactant selected from the group of zwitter-ionic surfactants.
14. The device according to claim 13 , selected from the group consisting of displays, mobile devices, light emitting devices, and solar cells.
15. A device according to claim 13 , selected from the group consisting of LCD displays or a quantum dot LEDs.
16. An article comprising a substrate and a coating, said coating comprising luminescent crystals of formula
M 1 a M 2 b X c (I),
wherein:
M 1 represents one or more alkaline metals selected from Cs, Rb, K, Na, and Li,
M 2 represents one or more metals selected from the group consisting of Ge, Sn, Pb, Sb, and Bi,
X represents one or more halogenides selected from the group consisting of Cl, Br, and I,
a represents 1-4,
b represents 1-2,
c represents 3-9;
and surfactant selected from the group of zwitter-ionic surfactants.
17. A method for manufacturing an intermediate good comprising a sheet-like substrate coated with one or more layers, wherein at least one of the layers is a functional layer, the method comprising the steps of:
(a) providing a substrate, and
(b) forming a solid polymer according to claim 6 to said substrate by applying a suspension comprising the luminescent crystals, the surfactant and at least one polymer or pre-polymer selected from the group of acrylates, epoxies, urethanes, styrenes, and silicones, followed by drying and/or curing, said solid polymer composition being said functional layer.