Fabrication process for A/M/X materials

1. A process for producing a crystalline A/M/X material, which crystalline A/M/X material comprises a compound of formula:

[A] a [M] b [X] c

wherein:

[A] comprises one or more A cations, wherein each A cation is selected from (H 2 N—C(H)═NH 2 ) + , an alkali metal cation, C 1-10 alkylammonium, C 2-10 alkenylammonium, C 1-10 alkyliminium, C 3-10 cycloalkylammonium and C 3-10 cycloalkyliminium optionally substituted with one or more substituents selected from amine, C 1-6 alkylamine, imine, C 1-6 alkylimine, C 1-6 alkyl, C 2-6 alkenyl, C 3-6 cycloalkyl and C 6-12 aryl;

[M] comprises one or more M cations which are metal or metalloid cations, wherein each M cation is selected from Pd 4+ , W 4+ , Re 4+ , Os 4+ , Ir 4+ , Pt 4+ , Sn 4+ , Pb 4+ , Ge 4+ , Te 4+ , Ca 2+ , Sr 2+ , Cd 2+ , Cu 2+ , Ni 2+ , Mn 2+ , Fe 2+ , Co 2+ , Pd 2+ , Ge 2+ , Sn 2+ , Pb 2+ , Yb 2+ , Eu 2+ , Li + , Na + , K + , Rb + , Cs + , Cu + , Ag + , Au + , Hg + , Bi 3+ , Sb 3+ , Cr 3+ , Fe 3+ , Co 3+ , Ga 3+ , As 3+ , Ru 3+ , Rh 3+ , In 3+ , Ir 3+ and Au 3+ ;

[X] comprises one or more X anions, wherein each X anion is selected from F − , Cl − , Br − and I − ;

a is a number from 1 to 6;

b is a number from 1 to 6; and

c is a number from 1 to 18,

the process comprising:

a) contacting an aqueous solution comprising an A precursor and an aqueous solvent with an organic solution comprising an M precursor and an organic solvent, wherein the organic solution comprises a hydrohalic acid; and

b) allowing a precipitate to form when the said aqueous and organic solutions are contacted,

wherein the process further comprises producing an optoelectronic device comprising the crystalline A/M/X material, and wherein the optoelectronic device is a light-emitting device.

2. A process according to claim 1 which is a process for preparing a thin film of said crystalline A/M/X material, the process further comprising:

c) optionally washing the precipitate;

d) dissolving the precipitate in an organic solvent to form a film-forming solution; and

e) dispersing the film-forming solution on a substrate,

wherein said optoelectronic device is an optoelectronic device comprising the thin film of the crystalline A/M/X material.

3. A process according to claim 1 which is a process for preparing a thin film of said crystalline A/M/X material, the process further comprising:

c′) optionally washing the precipitate;

d′) vapourising the precipitate; and

e′) depositing the vapourised precipitate on a substrate,

wherein said optoelectronic device is an optoelectronic device comprising the thin film of the crystalline A/M/X material.

4. A process according to claim 1 wherein said one or more A cations are monocations and said one or more M cations are dications.

5. A process according to claim 1 wherein the compound of formula [A] a [M] b [X] c is a compound of formula [A][M][X] 3 or [A] 2 [M][X] 6 .

6. A process according to claim 1 wherein the crystalline A/M/X material comprises two or more compounds of formula [A] a [M] b [X] c .

7. A process according to claim 1 wherein [A] comprises two or more different A cations.

8. A process according to claim 7 wherein the process comprises, prior to step (a), preparing the aqueous solution by combining a solution of a first A precursor with a solution of a second A precursor,

wherein:

the first A precursor comprises a first A cation; and

the second A precursor comprises a second A cation.

9. A process according to claim 1 wherein [X] comprises two or more different X anions.

10. A process according to claim 9 wherein the process comprises, prior to step (a), preparing the organic solution by combining a solution of a first M precursor with a solution of a second M precursor,

wherein:

the first M precursor comprises a first X anion; and

the second M precursor comprises a second X anion.

11. A process according to claim 1 wherein the organic solution comprises a hydrohalic acid of formula HX′, wherein X′ is one of the X anions.

12. A process according to claim 1 wherein each A cation is selected from Cs + , Rb + , (H 2 N—C(H)═NH 2 ) + , methylammonium, ethylammonium, propylammonium, butylammonium, pentylammoium, hexylammonium, septylammonium, octylammonium, and guanidinium.

13. A process according to claim 1 wherein each A precursor is a halide salt of the A cation or one of the A cations, and/or each M precursor is a halide salt of the M cation or one of the M cations.

14. A process according to claim 1 wherein each metal or metalloid M cation is selected from Ca 2+ , Sr 2+ , Cd 2+ , Cu 2+ , Ni 2+ , Mn 2+ , Fe 2+ , Co 2+ , Pd 2+ , Ge 2+ , Sn 2+ , Pb 2+ , Yb 2+ and Eu 2+ .

15. A process according to claim 1 wherein each X anion is selected from I − and Br − .

16. A process according to claim 1 wherein the organic solvent in the organic solution comprises a polar organic solvent.

17. A process according to claim 1 wherein the organic solvent of step (d) comprises a polar solvent.

18. A process according to claim 2 wherein the process further comprises:

f) removing the organic solvent from the film-forming solution on the substrate.

19. A process according to claim 1 wherein the optoelectronic device is a light emitting diode or a charge injection laser.

20. A process according to claim 1 wherein the optoelectronic device is an optoelectronic device wherein the crystalline A/M/X material functions as a phosphor.

21. A process according to claim 20 wherein the optoelectronic device is a display screen or a solid-state lighting device.

22. A process for producing a crystalline A/M/X material, which crystalline A/M/X material comprises a compound of formula:

[A] a [M] b [X] c

wherein:

[A] comprises one or more A cations, wherein each A cation is selected from (H 2 N—C(H)═NH 2 ) + , an alkali metal cation, C 1-10 alkylamammonium, C 2-10 alkenylammonium, C 1-10 alkyliminium, C 3-10 cycloalkylamammonium and C 3-10 cycloalkyliminium optionally substituted with one or more substituents selected from amine, C 1-6 alkylamine, imine, C 1-6 alkylimine, C 1-6 alkyl, C 2-6 alkenyl, C 3-6 cycloalkyl and C 6-12 aryl;

[M] comprises one or more M cations which are metal or metalloid cations, wherein each M cation is selected from Pd 4+ , W 4+ , Re 4+ , Os 4+ , Ir 4+ , Pt 4+ , Sn 4+ , Pb 4+ , Ge 4+ , Te 4+ , Ca 2+ , Sr 2+ , Cd 2+ , Cu 2+ , Ni 2+ , Mn 2+ , Fe 2+ , Co 2+ , Pd 2+ , Ge 2+ , Sn 2+ , Pb 2+ , Yb 2+ , Eu 2+ , Li + , Na + , K + , Rb + , Cs + , Cu + , Ag + , Au + , Hg + , Bi 3+ , Sb 3+ , Cr 3+ , Fe 3+ , Co 3+ , Ga 3+ , As 3+ , Ru 3+ , Rh 3+ , In 3+ , Ir 3+ and Au 3+ ;

[X] comprises one or more X anions, wherein each X anion is selected from F − , Cl − , Br − and I − ;

a is a number from 1 to 6;

b is a number from 1 to 6; and

c is a number from 1 to 18,

the process comprising:

a) contacting an aqueous solution comprising an A precursor and an aqueous solvent with an organic solution comprising an M precursor and an organic solvent, wherein the organic solution comprises a hydrohalic acid; and

b) allowing a precipitate to form when the said aqueous and organic solutions are contacted,

and wherein the process further comprises using the crystalline A/M/X material as a photo-emitter or as a phosphor.

23. A process according to claim 1 wherein each metal or metalloid M cation is Pb 2+ .

24. A process according to claim 1 wherein the organic solvent in the organic solution comprises DMF.

25. A process according to claim 1 wherein the organic solvent of step (d) comprises DMSO and/or DMF.