Fabrication process for a/m/x materials

Abstract

The invention relates to 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; [M] comprises one or more M cations which are metal or metalloid cations; [X] comprises one or more X anions; 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 is capable of producing crystalline A/M/X materials while precisely controlling their stoichiometry, leading to products with finely tunable optical properties such as peak emission wavelength. The invention also relates to process for producing a thin film comprising the crystalline A/M/X material of the invention, and to a thin film obtainable by the process of the invention. An optoelectronic device comprising the thin film is also provided.

1 - 29 . (canceled) 
     
     
         30 . A process for producing a crystalline A/M/X material, which crystalline A/M/X material comprises a compound of formula:
                       wherein:
 [A] comprises one or more A cations; 
 [M] comprises one or more M cations which are metal or metalloid cations; 
 [X] comprises one or more X anions; 
 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; and 
 b) allowing a precipitate to form when the said aqueous and organic solutions are contacted, 
   and wherein the process further comprises producing an optoelectronic device comprising the crystalline A/M/X material,   wherein the optoelectronic device is a photovoltaic device.   
     
     
         31 . A process according to  claim 30  which is a process for preparing a thin film of said crystalline A/M/X material, the process further comprising:
 a) optionally washing the precipitate; 
 b) dissolving the precipitate in an organic solvent to form a film-forming solution; and 
 c) dispersing the film-forming solution on a substrate, 
 wherein said optoelectronic device comprises the thin film of the crystalline A/M/X material. 
 
     
     
         32 . A process according to  claim 30  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 said crystalline A/M/X material. 
 
     
     
         33 . A process according to  claim 30  wherein said one or more A cations are monocations and said one or more M cations are dications. 
     
     
         34 . A process according to  claim 30  wherein the compound of formula [A] a[ M] b[ X] c  is a compound of formula [A][M][X] 3 . 
     
     
         35 . A process according to  claim 30  wherein the compound of formula [A] a[ M] b[ X] c  is a compound of formula [A] 2 [M][X] 6 . 
     
     
         36 . A process according to  claim 30  wherein the crystalline A/M/X material comprises two or more compounds of formula [A] a [M] b [X] c . 
     
     
         37 . A process according to  claim 30  wherein [A] comprises two or more different A cations. 
     
     
         38 . A process according to  claim 37  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. 
 
     
     
         39 . A process according to  claim 30  wherein [X] comprises two or more different X anions. 
     
     
         40 . A process according to  claim 39  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. 
 
     
     
         41 . A process according to  claim 30  wherein the organic solution comprises a hydrohalic acid. 
     
     
         42 . A process according to  claim 30  wherein the organic solution comprises a hydrohalic acid of formula HX′, wherein X′ is one of the X anions. 
     
     
         43 . A process according to  claim 30  wherein the relative molar amounts of each of said one or more A cations, said one or more M cations and said one or more X anions in the aqueous solution together with the organic solution are equal to the relative molar amounts of each of said one or more A cations, said one or more M cations and said one or more X anions in the compound of formula [A] a [M] b [X] c . 
     
     
         44 . A process according to  claim 30  wherein each A cation is selected from 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; preferably one or more of Cs + , Rb + , methylammonium, ethylammonium, propylammonium, butylammonium, pentylammoium, hexylammonium, septylammonium, octylammonium, and guanidinium. 
     
     
         45 . A process according to  claim 30  wherein each A precursor is a halide salt of the A cation or one of the A cations. 
     
     
         46 . A process according to  claim 30  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+ , preferably Sn 2+ , Pb 2+ , Cu 2+ , Ge 2+ , and Ni 2+ ; particularly preferably Pb 2+ . 
     
     
         47 . A process according to  claim 30  wherein each M precursor is a halide salt of the M cation or one of the M cations. 
     
     
         48 . A process according to  claim 30  wherein each X anion is selected from F - , Cl - , Br- or I - , preferably Cl -  or Br - . 
     
     
         49 . A process according to  claim 30  wherein [A] a[ M] b[ X] c  comprises at least two different A cations and at least two different X anions. 
     
     
         50 . A process according to  claim 30  wherein [A] comprises Cs +  and Rb +  and wherein [X] comprises Br -  and Cl - . 
     
     
         51 . A process according to  claim 30  wherein said aqueous solvent comprises less than 20% by volume of organic solvents, preferably less than 10% by volume of organic solvents. 
     
     
         52 . A process according to  claim 30  wherein the organic solvent in the organic solution comprises less than 20% by volume of water, preferably less than 10% by volume of water. 
     
     
         53 . A process according to  claim 30  wherein the organic solvent in the organic solution comprises a polar organic solvent, preferably an organic solvent that is miscible with water, further preferably DMF. 
     
     
         54 . A process according to  claim 30  wherein the organic solvent of step (d) comprises a polar solvent, preferably DMSO and/or DMF. 
     
     
         55 . A process according to  claim 30  wherein step (e) comprises spin-coating the film-forming solution on the substrate. 
     
     
         56 . A process according to  claim 30  wherein the process further comprises:
 d) removing the organic solvent from the film-forming solution on the substrate, 
 preferably by evaporation, preferably at a temperature of 15 to 150° C., also preferably for at least 1 minute. 
     
     
         57 . A process according to  claim 30  wherein the photovoltaic device is a solar cell. 
     
     
         58 . An optoelectronic device which is obtainable by or obtained by a process as defined in  claim 30 , wherein the optoelectronic device is a photovoltaic device. 
     
     
         59 . An optoelectronic device according to  claim 58  wherein the photovoltaic device is a solar cell.