Luminescent crystals and manufacturing thereof

1. A method for manufacturing luminescent crystals of 2-50 nm size,

said luminescent crystals being selected from compounds 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, 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;

said method comprising the steps of:

(a) providing a solid material, said solid material (i) having a stoichiometric composition of a moles M 1 , b moles M 2 and c moles X and (ii) having an average particle size of at least 15 nm and a poly-disperse size distribution;

(b) dispersing said material in the presence of a liquid, whereby said liquid being selected from (i) liquid surfactants, (ii) a combination of surfactant and solvent, (iii) a combination of surfactant, solvent and pre-polymer or polymer and (iv) a combination of surfactant and liquid pre-polymer; and whereby said dispersing is effected by agitated milling balls.

2. The method according to claim 1 whereby dispersing of step (b)

is effected by agitated milling balls with a ball size between 10-1000 μm; and/or

is effected with a specific power input per weight of suspension of at least 100 W/kg; and/or

is effected at a temperature below 120° C.

3. The method according to claim 1 , wherein said luminescent crystals are selected from the group of CsPbX 3 .

4. The method according to claim 1 , wherein said solvents are selected from the group of aliphatic hydrocarbons, aromatic hydrocarbons, ethers, esters, alcohols, and ketones.

5. The method according to claim 1 , wherein said surfactants are selected from the group of non-ionic, anionic, cationic and zwitter-ionic surfactants.

6. The method according to claim 1 , wherein said pre-polymer is selected from the group of acrylates, carbonates, sulfones, epoxies, vinyls, urethanes, imides, esters, furanes, melamines, styrenes, and silicones.

7. The method according to claim 1 , wherein in step (a) said solid material

is obtained by a dry synthetic process selected from a process consisting of; gas phase reaction and dry milling; or

by a wet synthetic process; or

is in situ formed by stoichiometric reaction of two or more precursors that comply with the net stoichiometric composition of formula (I).

8. The method according to claim 7 , wherein

said dry synthetic process is a gas phase process including decomposition and pyrolysis processes;

said wet synthetic process is a precipitation process from a solvent based or aqueous phase; and

said in situ formation takes place upon ball-milling the starting materials in the presence of surfactant and optionally solvent and/or liquid pre-polymer, wherein the surfactant is liquid if the solvent and/or liquid pre-polymer are not present.

9. The method according to claim 1 , wherein:

the weight ratio of said solid material:liquid material (solvent+surfactant) is in the range of 0.0001-0.5; or

the weight ratio of said surfactant:solid material is in the range of 100-0.1.

10. The method according to claim 1 further comprising:

the step of replacing one or more halide atom X of synthesized luminescent crystals with other halide atoms by anion exchange; and/or

the step of combining two or more types of luminescent crystals of formula (I).

11. The method according to claim 1 , wherein said pre-polymer is an acrylate.

12. 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, 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 non-ionic, anionic, cationic and zwitter-ionic surfactants; but excluding oleyl amine, oleic acid and trioctylphosphine; and

(iii) optionally solvent, said solvent selected from the group of aliphatic hydrocarbons, esters, alcohols, ketones; and

(iv) optionally polymer or pre-polymer selected from the group of acrylates, epoxies, urethanes, styrenes, silicones and cyclic olefinic copolymers.

13. The composition according to claim 12 , 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.

14. A composition according to claim 12 ,

wherein the surfactant is selected from the group of anionic, cationic, non-ionic and zwitter-ionic surfactants; and

wherein said surfactants comprise apolar end-groups selected from the group of alkyl or alkyl-ether chains with 4-30 carbon atoms.

15. A composition according to claim 12 ,

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.

16. A composition according to claim 12 ,

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.

17. 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, 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 non-ionic, anionic, cationic and zwitter-ionic surfactants; but excluding oleyl amine, oleic acid and trioctylphosphine; and

(iv) a hardened/cured polymer.

18. The solid polymer composition according to claim 17 , 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.

19. A composition according to claim 17 for converting blue light into white light.

20. The solid polymer composition of claim 17 , 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.

21. A composition according to claim 17 for converting blue light into white light in a light emitting diode (LED) or in a liquid crystal display.

22. 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 17 .

23. An intermediate good according to claim 22 , wherein said functional layer converts blue light into white light.

24. 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):

M 1 a M 2 b X c   (I),

wherein:

M 1 represents one or more alkaline metals selected from Cs, Rb, K, Na, 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 non-ionic, anionic, cationic and zwitter-ionic surfactants, but excluding oleyl amine, oleic acid and trioctylphosphine.

25. The device according to claim 24 , selected from the group consisting of displays, mobile devices, light emitting devices, and solar cells.

26. A device according to claim 24 , selected from the group consisting of LCD displays or a quantum dot LEDs.

27. An article comprising a substrate and a coating, said coating comprising luminescent crystals 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, 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 non-ionic, anionic, cationic and zwitter-ionic surfactants, but excluding oleyl amine, oleic acid and trioctylphosphine.

28. 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) depositing a solid polymer composition according to claim 17 to said substrate, the solid polymer composition formed 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, silicones and cyclic olefinic copolymers, followed by drying and/or curing, said solid polymer composition being said functional layer.