Stable A / M / X materials

Abstract

The present invention relates to a method for preparing a stable crystalline A / M / X material, wherein the material comprises a compound of formula [Z] p O q Oxide and formula [A] a [M] b [X] c A compound of the invention, wherein [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV; p and q are positive numbers; [A] comprises one or more A cations; [M] comprises one or more M cations; [X] comprises one or more X anions; a is an integer from 1 to 6; b is an integer from 1 to 6; and c is an integer from 1 to 18. Typically, the stable crystalline A / M / X material is a perovskite. The invention also provides a stable crystalline A / M / X material that can be produced by the method of the invention. The invention further provides materials and devices containing the stable crystalline A / M / X material of the invention.

Description

[0001] The project for this application was awarded by Marie Funding from the European Union’s Horizon 2020 research and innovation framework programme under grant agreement No 706552. Technical Field

[0002] The present invention relates to a method for producing an oxide and a a [M] b [X] c The present invention also provides a stable crystalline A / M / X material, which comprises a compound of formula [A] a [M] b [X] c The present invention also provides a stable crystalline A / M / X material, which is a polycrystalline material, comprising a plurality of crystallites containing the A / M / X material and oxides distributed along the grain boundaries between the crystallites. The present invention also relates to an optoelectronic device comprising a stable A / M / X material. Background Art

[0003] There is a great demand worldwide for photoactive semiconductor materials, which can convert electrical energy into light and vice versa. Such materials are useful in a wide range of semiconductor devices. For example, light-emitting materials can be used in the production of fluorescent screens and light-emitting diodes (LEDs), among other applications. Light-absorbing materials are in great demand in the production of solar cells.

[0004] Currently, organic substances are widely used to manufacture devices such as light-emitting devices. However, a disadvantage of organic substances is that they often emit very weakly in the blue light region of the visible spectrum. Organic LEDs (OLEDs) typically achieve a conversion efficiency of 20% in the red and green regions of the visible light emission spectrum. However, they often only achieve a conversion efficiency of up to 10% in the blue region of the visible spectrum. A key reason is that efficient red and green emission in OLEDs relies on the radiative recombination of singlet and triplet excitons. The universal spin-forbidden triplet-triplet electronic transitions in organic emitters are made possible by the introduction of phosphorescent metal complexes. However, such metal complexes are often not available or lack stability and efficiency in the blue region of the spectrum.

[0005] Inorganic materials such as perovskites do not have the same difficulty in undergoing spin-forbidden transitions as organic substances. Therefore, there is great interest in providing inorganic photoactive materials that can emit strongly in the blue region of the visible spectrum.

[0006] However, to date, great difficulties have been encountered in providing inorganic materials that are stable and emit strongly in the blue region of the visible spectrum. Many inorganic materials of interest have been found to chemically degrade when exposed to light, oxygen and moisture. In addition, the emission wavelength of these materials has been found to change over time, which is generally unacceptable for lighting and display applications, thus limiting the commercial application of these materials.

[0007] Perovskite materials, and especially lead halide perovskites, are ideal candidates as photoactive materials because they are highly emissive semiconductor materials. Lead halide perovskites are materials of the formula APbX3, where X is one or more halide ions. However, to date, most highly emissive perovskites with blue emission spectra ("highly emissive perovskites" refer to perovskites with a radiative external quantum efficiency of more than 20% in thin films) have the above-mentioned problems. Specifically, they exhibit poor stability in light and air.

[0008] For example, the paper “Blue-green color tunable solution processable organolead chloride-bromide mixed halideperovskites for optoelectronic applications” by Sadhanala et al., Nano Letters, 15(9), pp6095-6101 clearly shows that the addition of chloride ions to the perovskite MAPbBr3 is detrimental to its photoluminescence lifetime. That is, the presence of chloride ions increases the defect concentration in the perovskite and reduces its photoluminescence lifetime.

[0009] A possible solution to the poor stability of perovskite materials has been proposed in the application WO2017 / 001542. This document describes a method for depositing an encapsulation matrix or layer on a film comprising perovskite crystals. The technique uses trimethylaluminum (TMA) to crosslink aliphatic ligands on the surface of each perovskite crystal for encapsulating green-emitting perovskite CsPbBr3 nanoparticles. The same technique has also been used to encapsulate red-emitting perovskite CsPb(Br 1-x I x )3 nanoparticles. The encapsulated green and red nanoparticles showed good photoluminescence quantum efficiency after encapsulation. However, when trying to encapsulate the blue-emitting CsPb(Br 1-x Cl x)3 perovskite. It was found that the photoluminescence quantum efficiency of such materials was significantly reduced after encapsulation. In addition, upon irradiation, the emission wavelength of such materials was found to shift significantly toward the red. This red shift in the emission spectrum is attributed to halide segregation (Li et al., "Highly efficient perovskitenanocrystal light-emitting diodes enabled by a universal crosslinking method", Adv. Mater., vol. 28, pp 3528-3534, 2016).

[0010] Another difficulty with the method of WO2017 / 001542 is that a vapor deposition step is required. This step adds complexity to the method of producing perovskites for photoactive materials and is incompatible with printing techniques used, for example, to make optoelectronic devices. In addition, the perovskite may degrade before the encapsulation step is performed.

[0011] In applications such as manufacturing solar cells, where small changes in the absorption onset wavelength can cause significant performance losses, the degradation of perovskite performance is undesirable. Therefore, there remains a need for a simple method to produce stable materials, especially perovskite materials, which can be used to provide stable blue-emitting materials, such as perovskites. There is also a need for A / M / X materials obtained by this method. Summary of the invention

[0012] The inventors have now provided a new technique for preparing crystalline A / M / X materials having excellent stability and, therefore, an extremely long service life. The method involves exposing a relevant precursor of the crystalline A / M / X material to an oxide precursor. Thus, the oxide precursor is present during the formation of the A / M / X material and a stable oxide is immediately formed on the A / M / X material. It is speculated that the formation of the oxide and the A / M / X material stabilized by the oxide together provide direct protection for the stable A / M / X material from environmental factors such as water and oxygen. This can result in the excellent stability observed in the products of the method of the present invention.

[0013] Thus, the present invention provides a method for producing a stable crystalline A / M / X material comprising formula [Z] p O q Oxide and formula [A] a [M] b [X] c The compound

[0014] in:

[0015] [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV;

[0016] p and q are positive numbers;

[0017] [A] comprises one or more A cations;

[0018] [M] comprises one or more M cations;

[0019] [X] comprises one or more X anions;

[0020] a is an integer from 1 to 6;

[0021] b is an integer from 1 to 6; and

[0022] c is an integer from 1 to 18,

[0023] Furthermore, the method comprises treating the following substances with an oxide precursor comprising element Z:

[0024] (a) an A precursor comprising an A cation; and

[0025] (b) M precursor including M cation.

[0026] The method of the present invention can be conveniently carried out in solution. Solution phase processes have advantages over gas phase processes because they can avoid the need for more expensive vacuum equipment and are compatible with high fidelity printing techniques. Therefore, in a preferred method of the present invention, each of the A precursor, the M precursor and the oxide precursor is in solution.

[0027] Another surprising advantage of the present invention is that, unlike previous coating techniques, it can be used to stabilize crystalline A / M / X materials that emit blue light without causing excessive loss of photoluminescence or shifting the emission wavelength to the blue region. In fact, in some embodiments, when the stabilized A / M / X material is a blue-emitting material, the stabilized A / M / X material has the same or even better photoluminescence quantum yield (PLQY) than the corresponding A / M / X material without the stabilizing oxide present.

[0028] Thus, in preferred embodiments of the methods of the present invention, the stable A / M / X material emits light in the blue region of the visible spectrum, for example, light having a wavelength of less than 500 nm, preferably less than 495 nm or less than 490 nm. It is particularly preferred that the emission spectrum has a maximum between 460 and 480 nm. For example, in some embodiments, the stable A / M / X material comprises an A / M / X material of the formula [A][M][X]3, wherein [A] comprises two or more different A cations, and / or [X] comprises two or more different X anions.

[0029] The present invention also provides a product obtainable and / or obtained by the method of the present invention.

[0030] The present invention further provides a compound comprising formula [A] a [M] b [X] c A stable crystalline A / M / X material having a crystal of a compound of formula [Z] on its entire surface p O q An oxide coating layer, wherein:

[0031] [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV;

[0032] p and q are positive numbers;

[0033] [A] comprises one or more A cations;

[0034] [M] comprises one or more M cations;

[0035] [X] comprises one or more X anions;

[0036] a is an integer from 1 to 6;

[0037] b is an integer from 1 to 6; and

[0038] c is an integer of 1-18.

[0039] The stable crystalline A / M / X material may be polycrystalline. Therefore, the present invention further provides a stable crystalline A / M / X material, which is a polycrystalline material comprising a compound of formula [A] a [M] b [X] c A plurality of crystallites of a compound and a plurality of grain boundaries between the crystallites, wherein the formula [Z] p O q The oxides are distributed along the grain boundaries, where

[0040] [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV;

[0041] p and q are positive numbers;

[0042] [A] comprises one or more A cations;

[0043] [M] comprises one or more M cations;

[0044] [X] comprises one or more X anions;

[0045] a is an integer from 1 to 6;

[0046] b is an integer from 1 to 6; and

[0047] c is an integer of 1-18.

[0048] The stable crystalline A / M / X material of the present invention has an extraordinary stability, which means that it can maintain its photoluminescent properties for a long time. For example, it has been demonstrated that the stable A / M / X material of the present invention can maintain its photoluminescent quantum yield of more than 15% without decay for 6000 hours when exposed to simulated full-spectrum sunlight at high temperature (see Figure 5 ).

[0049] Furthermore, depending on the selection of [A], [M] and [X] and their relative proportions, the stable crystalline A / M / X materials of the present invention can emit light in the blue region of the visible spectrum with surprisingly high photoluminescence quantum yields, and of course also with excellent stability. For example, the stable A / M / X materials of the present invention have been demonstrated to emit light at 475 nm for 300 hours with a quantum yield exceeding 12%. In contrast, the PLQY of the unstabilized A / M / X materials (containing no oxide) at this wavelength does not exceed 8%, decaying to less than 1% during the measurement period (see Figure 7 ).

[0050] Thus, in a preferred aspect, the stable crystalline A / M / X material of the present invention comprises an A / M / X material of the formula [A][M][X]3, wherein [A] comprises two or more different A cations, and / or [X] comprises two or more different X anions. In a particularly preferred aspect of this embodiment, [A] comprises two different A cations, one of which is Cs + , the other is R b + This stable A / M / X material is a strong blue emitter.

[0051] The stable A / M / X material of the present invention may be provided in any form. For example, the present invention provides a coarse-grained powder comprising the stable A / M / X material defined herein; the present invention also provides a film comprising the stable A / M / X material defined herein.

[0052] The excellent stability and favorable optical properties of the stable crystalline A / M / X materials of the present invention are highly desirable in the production of optoelectronic devices. Therefore, the present invention provides an optoelectronic device comprising a stable A / M / X material as defined herein, such as a coarse-grained powder or a thin film as defined herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1Normalized photoluminescence ("PL") spectra of CsPbBr3 nanocrystals (a) protected by PVB, EVA, and (b) dispersed in polymethyl methacrylate (PMMA) or polystyrene (PS) deposited on glass substrates by spin coating are shown. The samples were exposed to simulated sunlight for 12 hours.

[0054] Figure 2 The stability of CsPbBr3 thin films deposited from nanocrystal (NCs) colloidal solutions and perovskite precursors (thin films) exposed to simulated sunlight was demonstrated by showing the PLQY over 150 h.

[0055] Figure 3 It shows that different Al 3+ / Pb 2+ Absorption spectrum of CsPbBr3 thin film generated by precursor ( Figure 3 a), Steady-state photoluminescence spectrum ( Figure 3 b) and normalized steady-state fluorescence spectra ( Figure 3 c).

[0056] Figure 4 exist Figure 4 (a) shows the normalized PLQY of CsPbBr3 thin films and the effect of simulated sunlight (76 mW cm -2 , at 70°C). Figure 4 (b) shows the normalized steady-state photoluminescence spectrum of CsPbBr3 films prepared in the presence of TMA with slight changes in aging time.

[0057] Figure 5 The PLQY of CsPbBr3 thin films (including CsPbBr3 treated with TMA) is shown with simulated sunlight (76 mW·cm -2 , and the relationship between exposure time for up to 6000 hours at 70°C.

[0058] Figure 6 The absorption spectra of stable crystalline A / M / X materials prepared using TMA in an antisolvent in the presence of a TMA precursor (referred to as the TMA quenching method) are shown ( Figure 6 a) and normalized steady-state photoluminescence spectra ( Figure 6 b). Formula [A] a [M] b [X] c The compound is CsPb(Br 0.7 Cl 0.3 ) 3. The material was in the form of a thin film and it was prepared using different concentrations of TMA in an antisolvent.

[0059] Figure 7 Shown according to Figure 6 The contents (circles) and CsPb(Br) prepared without TMA (squares) 0.7 Cl 0.3 )3 PLQY of the film and simulated sunlight (76 mW cm -2 , at 70°C) for 300 hours.

[0060] Figure 8 The TMA-quenched CsPb(Br) at different TMA-quenching times are shown. 0.7 Cl 0.3 )3 films. The films represented by squares ("during spin coating") are Figure 6 prepared as discussed above; the film indicated by the circle (“after crystallization”) involves 0.7 Cl 0.3 )3 After crystallization occurs, TMA is added. DETAILED DESCRIPTION

[0061] As described above, the present invention provides a method for producing a stable A / M / X product; a stable A / M / X material obtained and / or obtainable by the method of the present invention; a stable A / M / X material; a thin film or coarse-grained powder comprising a stable A / M / X material; and an optoelectronic device comprising the stable A / M / X material of the present invention.

[0062] These will now be described in detail. It should be noted that the following definitions are general and apply to both the product of the present invention and the method of the present invention. For example, for formula [A] a [M] b [X] c The description of the compounds applies equally to the compounds contained in the products of the process of the invention and in the stabilized A / M / X material products of the invention.

[0063] definition

[0064] The term "stable" as used herein means that the A / M / X material of the present invention (or obtained by the method of the present invention or obtainable by the method of the present invention) is stable in the presence of an oxide. "Stable" means that the emission and absorption characteristics of the A / M / X material change less than the corresponding characteristics of an unstabilized A / M / X material over time.

[0065] The term "treatment" as used herein refers to any process that reacts or interacts one compound with another compound. A precursor compound treated with another precursor compound can be added to the other precursor as it is (e.g., in dissolved form or vapor form) or as an initial compound that is converted into the precursor compound itself by a certain process.

[0066] As used herein, the term "reaction mixture" refers to the gas or liquid resulting from the combination of the A precursor, the M precursor, and the oxide precursor. The term "reaction mixture" is used to refer to the combination of the A precursor, the M precursor, and the oxide precursor before, during, and after the precursors react together to produce a stable crystalline A / M / X material. Thus, immediately upon the combination of these precursors, the reaction mixture will contain a very small amount of stable crystalline A / M / X material. However, after these precursors have reacted for a period of time (e.g., a few seconds), the reaction mixture will contain a larger amount of stable crystalline A / M / X material and a smaller amount of the precursors.

[0067] The terms "organic compound" and "organic solvent" as used herein mean their typical meanings in the art and are easily understood by those skilled in the art.

[0068] As used herein, the term "disposed on" means that one component is provided or arranged on another component. The first component may be provided or placed directly on the second component, or there may be a third component interposed between the first and second components. For example, if a first layer is disposed on a second layer, this includes the case where there is an intermediate third layer between the first and second layers. However, in general, "disposed on" means that one component is arranged directly on another component.

[0069] The term "porous" as used herein refers to a material in which pores are arranged. Thus, for example, in a porous material, the pores are the volumes in the support where no material is present. The pores in the material may include "closed-cell" pores as well as open-cell pores. Closed-cell pores are pores in a material with non-connected cavities, i.e., pores that are isolated within the material and not connected to any other pores, so that liquids to which the material is exposed cannot enter such pores. On the other hand, "open-cell pores" may allow such liquids to enter. The concepts of open and closed-cell porosity are discussed in detail in J. Rouquerol et al. "Recommendations for the Characterization of Porous Solids", Pure & Appl. Chem., Vol. 66, No. 8, pp. 1739-1758, 1994. Therefore, open-cell porosity refers to the fraction of the volume in which fluid flow can effectively occur to the total volume of the porous material. Therefore, it does not include closed-cell pores. The term "open porosity" is interchangeable with "connected porosity" and "effective porosity" and is often simplified to "porosity" in the art. Therefore, "no open porosity" as used herein refers to a material without effective porosity. The term "non-porous" as used herein refers to a material without any porosity, that is, neither open porosity nor closed porosity.

[0070] As used herein, the term "layer" refers to any structure that is substantially laminar in form (e.g., extending substantially in two perpendicular directions, but having limited extension in a third perpendicular direction). The thickness of a layer may vary with the extent of the layer. Typically, a layer has an approximately constant thickness. As used herein, the "thickness" of a layer refers to the average thickness of the layer. The thickness of a layer can be readily measured, for example using a microscope, such as an electron microscope of a thin film cross section, or by surface profilometry, for example using a stylus profilometer.

[0071] As used herein, the term "band gap" refers to the energy difference between the top of the valence band and the bottom of the conduction band in a material. Of course, technicians can easily use well-known methods to measure the band gap of semiconductors (including the band gap of perovskites), which does not require too much experimentation. For example, the band gap of a semiconductor can be estimated by constructing a photovoltaic diode or a solar cell from a semiconductor and determining the photovoltaic action spectrum. Alternatively, the band gap is estimated by measuring the light absorption spectrum by transmission spectroscopy photometry or by photothermal deflection spectroscopy, or the band gap can be conveniently obtained from the photoluminescence spectrum. The band gap can be determined by making a Tauc diagram, as described in Tauc, J., Grigorovici, R. & Vancu, a. Optical Properties and Electronic Structure of Amorphous Germanium. Phys. Status Solidi 15, 627–637 (1966), wherein the square of the product of the absorption coefficient multiplied by the photon energy is plotted as the Y axis relative to the photon energy as the x axis, and the straight line intercept where the absorption edge intersects the x axis gives the optical band gap of the semiconductor. Alternatively, the optical band gap can be estimated by the starting value of the incident photon to electron conversion efficiency, as described in [Barkhouse DAR, Gunawan O, Gokmen T, Todorov TK, Mitzi DB. Device characteristics of a 10.1% hydrazineprocessed Cu2ZnSn(Se,S)4 solar cell. Progress in Photovoltaics: Research and Applications 2012; published online DOI: 10.1002 / pip.1160.].

[0072] As used herein, the term "semiconductor" or "semiconductor material" refers to a material having an electrical conductivity between that of a conductor and a dielectric. The semiconductor may be a negative (n) type semiconductor, a positive (p) type semiconductor, or an intrinsic (i) semiconductor. The semiconductor may have a band gap of 0.5 to 3.5 eV, such as a band gap of 0.5 to 2.5 eV or 1.0 to 2.0 eV (measured at 300 K).

[0073] As used herein, the term "n-type region" refers to a region of one or more electron transport (i.e., n-type) materials. Similarly, the term "n-type layer" refers to a layer of electron transport (i.e., n-type) material. The electron transport (i.e., n-type) material can be a single electron transport compound or single substance material, or a mixture of two or more electron transport compounds or single substances. The electron transport compound or single substance material can be undoped or doped with one or more doping elements.

[0074] As used herein, the term "p-type region" refers to a region of one or more hole transport (i.e., p-type) materials. Similarly, the term "p-type layer" refers to a layer of hole transport (i.e., p-type) materials. The hole transport (i.e., p-type) material can be a single hole transport compound or single substance material, or a mixture of two or more hole transport compounds or single substances. The hole transport compound or single substance material can be undoped or doped with one or more doping elements.

[0075] As used herein, the term "electrode material" refers to any material suitable for use in an electrode. The electrode material has a high electrical conductivity. As used herein, the term "electrode" refers to a region or layer consisting of or essentially consisting of an electrode material.

[0076] As used herein, the term "optionally substituted" means that the group concerned may or may not have a substituent, i.e., it may be unsubstituted or substituted. For example, the group may have 0, 1, 2, 3 or more substituents; typically 0, 1 or 2 substituents. Substituents may generally be selected from substituted or unsubstituted C1-C 20 alkyl, substituted or unsubstituted aryl (as defined herein), cyano, amino, C1-C 10 Alkylamino, di(C1-C 10 ) alkylamino, arylamino, diarylamino, arylalkylamino, amido, acylamido, hydroxy, oxo, halo, carboxyl, ester, acyl, acyloxy, C1-C 20 Alkoxy, aryloxy, halogenated alkyl, sulfonic acid, mercapto (i.e., thiol, -SH), C1-C 10 Alkylthio, arylthio and sulfonyl.

[0077] As used herein, an alkyl group may be a substituted or unsubstituted, straight chain or branched saturated group, and is typically a substituted or unsubstituted straight chain saturated group, more typically an unsubstituted straight chain saturated group. The alkyl group typically includes 1 to 20 carbon atoms, typically 1 to 10 carbon atoms. 1-10 Alkyl is an unsubstituted or substituted, straight-chain or branched saturated hydrocarbon group having 1 to 10 carbon atoms. 1-6 Alkyl is an unsubstituted or substituted, straight-chain or branched saturated hydrocarbon radical having 1 to 6 carbon atoms. Typically it is, for example, methyl, ethyl, propyl, isopropyl, n-propyl, butyl, tert-butyl, sec-butyl, n-butyl, pentyl or hexyl. Typically, alkyl is C 1-4Alkyl. If the term "alkyl" is used anywhere herein without a prefix specifying the number of carbon atoms, then the number of carbon atoms is generally from 1 to 20 (this also applies to any other organic group mentioned herein).

[0078] As used herein, an alkenyl group can be a substituted or unsubstituted, straight or branched unsaturated group, typically a substituted or unsubstituted straight chain unsaturated group, more often an unsubstituted straight chain unsaturated group. An alkenyl group can include one or more carbon-carbon double bonds, such as one, two or three double bonds. Typically, an alkenyl group includes one double bond. An alkenyl group typically includes 2 to 20 carbon atoms, typically 2 to 10 carbon atoms. 2-10 Alkenyl is an unsubstituted or substituted, straight-chain or branched, unsaturated hydrocarbon group having 2 to 10 carbon atoms. 2-6 Alkenyl is an unsubstituted or substituted, straight or branched unsaturated hydrocarbon radical having 2 to 6 carbon atoms. For example, typically it is vinyl, propenyl, prop-1-enyl, prop-2-enyl, butenyl, but-1-enyl, but-2-enyl, but-4-enyl, pentenyl, pent-1-enyl, pent-2-enyl, pent-3-enyl, pent-4-enyl, hexenyl, hex-1-enyl, hex-2-enyl, hex-3-enyl, hex-4-enyl or hex-5-enyl.

[0079] As used herein, a cycloalkyl group may be a substituted or unsubstituted cyclic saturated group, and is typically an unsubstituted cyclic saturated group. A cycloalkyl group typically includes 3 to 20 carbon atoms. 3-10 The cycloalkyl group is an unsubstituted or substituted cyclic saturated hydrocarbon group having 3 to 10 carbon atoms. 3-6 The cycloalkyl group is an unsubstituted or substituted cyclic saturated hydrocarbon group having 3 to 6 carbon atoms. For example, it is usually a cyclopropyl group, a cyclobutyl group, a cyclopentyl group or a cyclohexyl group.

[0080] As used herein, a cycloalkenyl group may be a substituted or unsubstituted cyclic unsaturated group, and is typically an unsubstituted cyclic unsaturated group. A cycloalkenyl group typically includes 3 to 20 carbon atoms. A cycloalkenyl group may include one or more double bonds (depending on the number of carbon atoms present in the ring). 4-10 The cycloalkenyl group is an unsubstituted or substituted cyclic unsaturated hydrocarbon group having 4 to 10 carbon atoms. 4-10 The cycloalkenyl group is an unsubstituted or substituted cyclic unsaturated hydrocarbon group having 3 to 6 carbon atoms. For example, typically it is a cyclobutenyl group, a cyclopentenyl group or a cyclohexenyl group.

[0081] As used herein, an alkoxy group is a group comprising an alkyl group as defined herein bonded to an oxy group. That is, an alkoxy group has the formula "-O-alkyl", wherein the alkyl group is as defined herein. Thus, C1-10 An alkoxy group is a group of the formula "-O-alkyl" wherein the alkyl group is a C 1-10 Alkyl group.

[0082] As used herein, an alkenyloxy group is a group comprising an alkenyl group as defined herein bonded to an oxy group. That is, an alkenyloxy group has the formula "-O-alkenyl," wherein the alkenyl group is as defined herein. Thus, C 1-10 An alkenyloxy group is a group of the formula "-O-alkenyl" wherein the alkenyl group is a C 1-10 Alkenyl group.

[0083] As used herein, the term "halide" refers to a singly charged anion of an element of Group VIII of the Periodic Table."Halide" includes fluoride, chloride, bromide and iodide.

[0084] As used herein, the term "halogen" refers to a halogen atom. Exemplary halogens include fluorine, chlorine, bromine and iodine.

[0085] As used herein, aryl is a substituted or unsubstituted, monocyclic or bicyclic aromatic group which generally contains 6 to 14 carbon atoms, usually 6 to 12 carbon atoms, preferably 6 to 10 carbon atoms in the ring portion. 6-12 Aryl is a substituted or unsubstituted monocyclic or bicyclic aromatic group containing 6 to 12 carbon atoms. Examples include phenyl, naphthyl, indenyl and indanyl.

[0086] As used herein, an amino group is a group of formula -NR2, wherein each R is a substituent. R is typically selected from hydrogen, alkyl, alkenyl, cycloalkyl, or aryl, wherein alkyl, alkenyl, cycloalkyl, and aryl are each as defined herein. Typically, each R is selected from hydrogen, C 1-10 Alkyl, C 2-10 Alkenyl and C 3-10 Preferably, R is independently selected from hydrogen, C 1-6 Alkyl, C 2-6 Alkenyl and C 3-6 More preferably, R is independently selected from hydrogen and C 1-6 alkyl.

[0087] A typical amino group is an alkylamino group, which is a group of the formula -NR2, wherein at least one R is an alkyl group as defined herein. 1-6 The alkylamino group is an alkylamino group containing 1 to 6 carbon atoms.

[0088] As used herein, an imino group is a group of formula R2C=N- or -C(R)=NR, wherein each R is a substituent. That is, an imino group is a group that includes a C=N moiety, having a radical moiety on the N atom or a radical moiety attached to the C atom of the C=N bond. R is as defined herein: that is, R is typically selected from hydrogen, alkyl, alkenyl, cycloalkyl, or aryl, wherein alkyl, alkenyl, cycloalkyl, and aryl are each as defined herein. Typically, each R is selected from hydrogen, C 1-10 Alkyl, C 2-10 Alkenyl and C 3-10 Preferably, R is independently selected from hydrogen, C 1-6 Alkyl, C 2-6 Alkenyl and C 3-6 More preferably, R is independently selected from hydrogen and C 1-6 alkyl.

[0089] A typical imino group is an alkylimino group, which is a group of the formula R2C=N- or -C(R)=NR, wherein at least one R is an alkyl group as defined herein. 1-6 Alkylimino groups are alkylimino groups wherein the R substituents comprise 1 to 6 carbon atoms.

[0090] The term "ester" as used herein refers to an organic compound of the formula "alkyl-C(=O)-O-alkyl" wherein the alkyl groups are the same or different and are as defined herein. The alkyl groups may be optionally substituted.

[0091] The term "ether" as used herein means an oxygen atom substituted with two alkyl groups as defined herein. The alkyl groups may be optionally substituted and may be the same or different.

[0092] The term "perovskite" as used herein refers to a material having a three-dimensional crystal structure related to the three-dimensional crystal structure of CaTiO3, or a material comprising a material layer, wherein the layer has a structure related to the CaTiO3 structure. A material having a three-dimensional crystal structure related to the three-dimensional crystal structure of CaTiO3 can be referred to as having a "3D perovskite structure", so a perovskite according to this definition can be referred to as a "3D perovskite". The structure of CaTiO3 can be represented by the formula ABX3, wherein A and B are cations of different sizes, and X is an anion. In the unit cell, cation A is at (0,0,0), cation B is at (1 / 2,1 / 2,1 / 2), and anion X is at (1 / 2,1 / 2,0). Cation A is generally larger than cation B. Those skilled in the art will appreciate that when A, B, and X vary, different ion sizes may cause the structure of the perovskite material to distort from the structure adopted by CaTiO3 to a distorted structure with lower symmetry. If the material includes a layer having a structure related to the CaTiO3 structure, the symmetry will also be reduced. Materials comprising a layer of perovskite material are well known. For example, a material structure using a K2NiF4-type structure includes a layer of perovskite material. These are referred to in the art as "2D layered perovskites" and are structurally different from the above-mentioned 3D perovskites. 2D layered perovskites can be represented by the formula [A]2[M][X]4, where [A] is at least one cation, [M] is at least one cation of a different size than cation A, and [X] is at least one anion.

[0093] Those skilled in the art will appreciate that a perovskite material can be represented by the formula [A][B][X]3, where [A] is at least one cation, [B] is at least one cation, and [X] is at least one anion. When the perovskite includes more than one A cation, different A cations can be distributed on the A sites in an ordered or disordered manner. When the perovskite includes more than one B cation, different B cations can be distributed on the B sites in an ordered or disordered manner. When the perovskite includes more than one X anion, different X anions can be distributed on the X sites in an ordered or disordered manner. The symmetry of a perovskite including more than one A cation, more than one B cation, or more than one X cation will be lower than the symmetry of CaTiO3.

[0094] As used herein, the term "metal halide perovskite" refers to a perovskite having a formula comprising at least one metal cation and at least one halide anion.

[0095] As used herein, the term "mixed halide perovskite" refers to a perovskite or mixed perovskite containing at least two types of halide anions.

[0096] As used herein, the term "mixed-cation perovskite" refers to a perovskite that is a mixed perovskite comprising at least two types of A cations.

[0097] The term "hexahalogenated metal salt" as used herein refers to a metal salt comprising the formula [MX6] n- The invention relates to a compound of an anion of , wherein M is a metal atom, X is each independently a halogen anion, and n is an integer of 1 to 4.

[0098] As used herein, the term "photoelectric device" refers to a device that sources, controls, detects, or emits light. Light is understood to include any electromagnetic radiation. Examples of optoelectronic devices include photovoltaic devices, photodiodes, solar cells, photodetectors, phototransistors, photomultipliers, photoresistors, color display devices, phototransistors, light emitting devices, light emitting diodes, and charge injection lasers.

[0099] The term "consisting essentially of" refers to a composition comprising a component consisting essentially of it and other components, provided that the other ingredients do not have a substantial effect on the basic characteristics of the composition. Typically, a composition consisting essentially of certain components will contain greater than or equal to 95 wt% of these components, or greater than or equal to 99 wt% of these components.

[0100] method

[0101] Thus, the method of the present invention comprises treating both an A precursor comprising A cations and an M precursor comprising M cations with an oxide precursor comprising element Z. Thus, the method of the present invention comprises contacting an A precursor as defined herein, an M precursor as defined herein and an oxide precursor as defined herein.

[0102] The method is typically performed in a fluid phase. In some embodiments, the method is performed in a gas phase. For example, in some embodiments, the method includes treating a gaseous A precursor and a gaseous M precursor with a gaseous oxide precursor.

[0103] In some embodiments, the method is performed in a liquid phase. For example, in some embodiments, the method includes treating an A precursor in solution and an M precursor in solution with an oxide precursor in solution.

[0104] In yet other embodiments, the method may involve a liquid phase and a gas phase. For example, the method may include treating an A precursor in solution and an M precursor in solution with a gaseous oxide precursor. "In solution" means that the relevant precursor is dissolved in a solution containing one or more solvents.

[0105] For reasons of convenience, embodiments in which the method is carried out in the liquid phase or in solution are preferred because they do not require the generation and control of vaporized precursor compounds. Therefore, preferably, one or more of the A precursor, the M precursor, and the oxide precursor are in solution. In a preferred embodiment of the method of the present invention, each of the A precursor, the M precursor, and the oxide precursor is in solution. In this case, the method may include treating the A precursor in solution and the M precursor in solution with the oxide precursor in solution.

[0106] A precursor, M precursor and oxide precursor may involve one or more solutions. In some embodiments, each precursor is initially present in different solutions at the beginning of the method of the present invention. For example, the method may include treating a first solution (the first solution includes an M precursor and a first solvent) with a second solution (the second solution includes an oxide precursor and a second solvent) and with a third solution (the third solution includes an A precursor and a third solvent). Typically, in these embodiments, the method includes mixing the first solution, the second solution and the third solution. For example, in one aspect of this embodiment, the method may include disposing the first solution, the second solution and the third solution together on a substrate.

[0107] In other embodiments, two precursors may be present in the same solution. Such embodiments may be preferred because they require less solution manipulation. Therefore, in typical examples of these embodiments of the inventive method, the A precursor and the M precursor are present in a first solution comprising an A precursor, an M precursor and a first solvent. That is, the method may include treating the first solution comprising an A precursor, an M precursor and a first solvent with an oxide precursor.

[0108] In some embodiments of the methods of the present invention, the oxide precursor is present in a second solution comprising the oxide precursor and a second solvent.

[0109] Typically, the method of the present invention involves two solutions. Thus, in the method of the present invention, one or more precursors may be present in a first solution and one or more precursors may be present in a second solution. An advantage of using two or more different solutions is that the precursors may remain separate and therefore do not react before the first and second solutions come into contact. For example, the method may comprise treating a first solution with a second solution, wherein:

[0110] The first solution includes an M precursor and a first solvent.

[0111] The second solution includes an oxide precursor and a second solvent; and

[0112] The first solution or the second solution includes an A precursor.

[0113] In a preferred aspect, the method may comprise treating the first solution with the second solution, wherein:

[0114] The first solution includes an A precursor, an M precursor, and a first solvent; and

[0115] The second solution includes an oxide precursor and a second solvent.

[0116] According to the above method, when the A precursor, M precursor and oxide precursor all meet, a reaction to form a stable A / M / X material will occur. This method produces a stable A / M / X material, rather than producing an A / M / X material, which is subsequently treated with an oxide precursor.

[0117] When there is a first solution, the first solution includes the first solvent and the M precursor. Therefore, generally, the first solvent is a solvent capable of dissolving the M precursor. Generally, the first solvent is an organic solvent, preferably a polar organic solvent. Polar organic solvents are preferred because they are generally capable of dissolving ionic compounds, and the M precursor is generally an organic compound. Suitable examples of the first solvent are dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and γ-butyrolactone (GBL).

[0118] It should be noted that the first solution may include one or more compounds and / or one or more solvents in addition to the M precursor compound and the first solvent. For example, the first solution may include a first solvent selected from dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL) and one or more additional solvents, each of which is typically selected from this group.

[0119] When there is a second solution, the second solution includes the second solvent and the oxide precursor. Therefore, generally, the second solvent is a solvent capable of dissolving the oxide precursor. Therefore, the nature of the second solvent is not particularly limited. Generally speaking, the second solvent is an organic solvent, which can be polar or non-polar. However, generally, the second solvent is a weakly polar or non-polar solvent. Generally, the second solvent can be selected from optionally substituted aromatic substances, optionally substituted esters and optionally substituted ethers. Exemplary second solvents include, for example, toluene, chlorobenzene, anisole, methyl acetate, ethyl acetate, diethyl ether, chloroform and dichlorobenzene.

[0120] It should be noted that the second solution may include one or more compounds and / or one or more solvents in addition to the oxide precursor compound and the second solvent. For example, the second solution may include a second solvent selected from an optionally substituted aryl substance, an optionally substituted ester, or an optionally substituted ether; and one or more additional solvents selected from this group. Specifically, the second solution may include a second solvent selected from toluene, chlorobenzene, anisole, methyl acetate, ethyl acetate, diethyl ether, chloroform, and dichlorobenzene and one or more additional solvents, each of which is typically selected from this group.

[0121] In some embodiments, the A precursor is present in the third solution. When the third solution is present, the third solution includes the third solvent and the A precursor. Therefore, generally, the third solvent is a solvent capable of dissolving the A precursor. Generally, the third solvent is an organic solvent, preferably a polar organic solvent. Polar organic solvents are preferred because they are generally capable of dissolving ionic compounds, and the A precursor is generally an organic compound. Suitable examples of the third solvent are dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and gamma-butyrolactone (GBL). The third solution may include one or more compounds and / or one or more solvents other than the A precursor compound and the third solvent. For example, the third solution may include a third solvent selected from dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), gamma-butyrolactone (GBL) and one or more additional solvents, each additional solvent being generally selected from the group.

[0122] Thus, in an exemplary embodiment of the method of the present invention, the method comprises treating the first solution with the second solution, wherein:

[0123] The first solution includes a first solvent and an M precursor including an M cation;

[0124] The second solution includes a second solvent and an oxide precursor including element Z;

[0125] The first solution or the second solution (preferably the first solution) includes an A precursor containing an A cation;

[0126] The first solvent is selected from dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) or gamma-butyrolactone (GBL); and

[0127] The second solvent is selected from toluene, chlorobenzene, anisole, methyl acetate, ethyl acetate, diethyl ether, chloroform or dichlorobenzene.

[0128] In a preferred embodiment of the method of the present invention, the method comprises the step of treating the A precursor, the M precursor and the oxide precursor with an antisolvent. The antisolvent is a solvent in which the stable A / M / X material is poorly soluble or insoluble. Here, "insoluble" and "poorly soluble" have their common meanings to those skilled in the art. Typically, the solubility of the stable A / M / X material in the antisolvent is less than 10 g / l, preferably less than 1 g / l, for example less than 0.1 g / l or less than 0.01 g / l.

[0129] Therefore, in a preferred embodiment of the method of the present invention, the method involves treating the A precursor and the M precursor with a second solution comprising an oxide precursor and a second solvent, wherein the formula [A] a [M] b [X] c The compound is insoluble in the second solvent. The second solution optionally includes an A precursor.

[0130] The antisolvent is typically a weakly polar or non-polar organic solvent. Exemplary antisolvents include substituted aromatic substances (typically substituted benzenes) or benzene, optionally substituted esters or optionally substituted ethers. Particularly preferably, the antisolvent is selected from toluene, chlorobenzene, anisole, methyl acetate, ethyl acetate, diethyl ether, chloroform, isopropanol, ethanol, methanol or dichlorobenzene.

[0131] In the case where the second solvent is an antisolvent, the second solution may include one or more additional solvents. For example, the second solution may include one or more additional solvents that are also antisolvents.

[0132] An advantage of an antisolvent is that it promotes precipitation of the stable A / M / X material of the present invention once formed.

[0133] The antisolvent need not be provided with any precursor material. Thus, in some embodiments, the method comprises treating the A precursor and the M precursor with an oxide precursor to form a reaction mixture, followed by treating the reaction mixture with an antisolvent as defined herein. For example, in one exemplary embodiment, the method comprises treating the first solution with the second solution to form a reaction mixture, wherein:

[0134] The first solution includes a first solvent and an M precursor including an M cation;

[0135] The second solution includes a second solvent and an oxide precursor containing element Z;

[0136] The first solution or the second solution (preferably the first solution) includes an A precursor containing an A cation; and

[0137] The reaction mixture is then treated with an antisolvent.

[0138] As mentioned above, each of the first solution, the second solution and the third solution may include additional components when present. However, in a preferred embodiment of the invention, each of these solutions (when present) does not contain aliphatic ligands. Therefore, in a preferred embodiment, the method of the present invention is carried out in the absence of aliphatic ligands.

[0139] "Aliphatic ligand" refers to a ligand that contains a hydrocarbon tail. Typical examples of aliphatic ligands include amines, aliphatic phosphates, and carboxylic acids. For example, aliphatic ligands include L 1 COOH and L 1 L 2 L 3 N, L 1 is selected from optionally substituted C4-C 20 Alkyl, C4-C 20 Alkenyl and C4-C 20 Cycloalkyl; preferably unsubstituted C4-C 20 Alkyl, C4-C 20 Alkenyl and C4-C 20 Cycloalkyl. 2 and L 3 Each is independently selected from H, optionally substituted C1-C6 alkyl, C2-C6 alkenyl and C3-C6 cycloalkyl; preferably H or unsubstituted C1-C6 alkyl, C2-C6 alkenyl and C3-C6 cycloalkyl; most preferably H.

[0140] In the method of the present invention, the oxide precursor produces the oxide [Z] p O q . This oxide is generated by oxidation of an oxide precursor. Therefore, in the method of the present invention, the oxide precursor is treated with an oxidizing agent. Suitable oxidizing agents include oxygen and water; the most common oxidizing agent is water. Therefore, in the method of the present invention, the treatment of the A precursor and the M precursor with the oxide precursor is usually carried out in the presence of water.

[0141] Typically, it is not necessary to include a step of adding an oxidant (e.g., water) in the method of the present invention. The oxide precursor is typically a reactive species that readily reacts with an oxidant (typically water). Typically, trace amounts of oxidants in the atmosphere (typically oxygen or water, most commonly water) or, for example, trace amounts of oxidants in the first solvent and / or the second solvent (if present) can be relied upon to provide sufficient oxygen for the method of the present invention.

[0142] In some embodiments, the method of the present invention includes treating the A precursor and the M precursor with an oxide precursor and water. As described above, water may be present in the atmosphere or in the solvent used by the method. Alternatively, water may be actively added to the reaction mixture. For example, the reaction may include the step of adding water to the first solvent (generally water is not added to the second solvent to avoid water reacting with the oxide precursor before the method of the present invention). In other embodiments, such as when the method is carried out in the vapor phase, the method may include providing water vapor or steam to the gaseous A precursor or the gaseous M precursor or to the gaseous reaction mixture. Typically, it is dependent on trace amounts of water or oxygen, and it is not necessary to actively add water or oxygen.

[0143] Typically, the method of the present invention produces a stable crystalline A / M / X material on a substrate. Thus, typically, the method involves treating the following with an oxide precursor comprising element Z in the presence of a substrate:

[0144] (a) an A precursor comprising an A cation; and

[0145] (b) M precursor including M cation.

[0146] The precursors may be mixed to form a reaction mixture, after which the reaction mixture is exposed to (e.g., disposed on) a substrate. However, in other embodiments, the method includes disposing one or more precursors on a substrate before treating the precursors with other precursors. The latter embodiment is preferred because it enables the production of stable crystalline A / M / X materials directly on a desired substrate.

[0147] In a preferred embodiment, the method includes placing the A precursor and the M precursor on a substrate before treating the A precursor and the M precursor with an oxide precursor.

[0148] In the case where the reaction is carried out in the gas phase, the method generally comprises exposing the gaseous reaction mixture to the substrate. In this embodiment, the method generally comprises treating the gaseous A precursor and the gaseous M precursor with a gaseous oxide precursor and optionally with water vapor in the presence of the substrate. For example, the method may comprise exposing a reaction mixture containing a gaseous A precursor, a gaseous M precursor, a gaseous oxide precursor and optionally water vapor to the substrate.

[0149] In the case where the reaction is carried out in the liquid phase, the method generally includes exposing the liquid reaction mixture to the substrate. In some embodiments, the method may first include preparing a liquid reaction mixture including an A precursor, an M precursor, and an oxide precursor, and then exposing the liquid reaction mixture to the substrate. In other embodiments, one or more precursors are disposed on the substrate prior to treatment with one or more other precursors.

[0150] Therefore, in some embodiments, the methods of the present invention include:

[0151] disposing a first solution on a substrate; and

[0152] treating the first solution with the second solution, wherein:

[0153] The first solution includes a first solvent and an M precursor including an M cation;

[0154] The second solution includes a second solvent and an oxide precursor containing element Z;

[0155] The first solution or the second solution (preferably the first solution) includes an A precursor containing an A cation.

[0156] The substrate is solid. The nature of the substrate is not particularly limited. For example, the substrate may simply be glass, such as a glass slide. More generally, the substrate is a material used to make an optoelectronic device as defined herein. For example, the substrate may include one or more of: a semiconductor; an n-type semiconductor; a p-type semiconductor; an electrode; a dielectric support material and a polymer as defined herein.

[0157] The method may include one or more preliminary steps to prepare the precursors. For example, when the method is performed entirely in the gas phase, the method may include generating each precursor in gaseous form. Such a method may involve heating the precursors, optionally under a low pressure inert gas atmosphere or under vacuum. The gaseous precursors may be generated together or separately.

[0158] When the method is performed in a solution, the method may include generating one or more solutions. For example, the method may include:

[0159] generating a first solution comprising an M precursor dissolved in a first solvent;

[0160] generating a second solution comprising an oxide precursor dissolved in a second solvent;

[0161] generating a third solution comprising the A precursor dissolved in a third solvent; and

[0162] The first solution and the third solution are treated with the second solution.

[0163] Preferably, the processing step of the method may involve merely mixing the two solutions. For example, the method may comprise:

[0164] A first solution is generated comprising an M precursor and an optional A precursor dissolved in a first solvent.

[0165] generating a second solution comprising an oxide precursor and optionally an A precursor dissolved in a second solvent; and

[0166] The first solution is treated with the second solution.

[0167] The method preferably further comprises disposing the first solution on the substrate, and optionally further comprises also disposing the second solution on the substrate.

[0168] The method of the present invention may also include the further step of processing the stable crystalline A / M / X material.

[0169] Typically, the method of the present invention further comprises recovering the stable crystalline A / M / X material from the reaction mixture. For example, the method of the present invention may further comprise removing any solvent present from the stable crystalline A / M / X material. Preferably, the method of the present invention comprises removing the first solvent and the second solvent from the stable crystalline A / M / X material. Other optional further method steps comprise washing the stable crystalline A / M / X material or drying the stable crystalline A / M / X material.

[0170] The product of the method is a product as described herein. Thus, the method of the present invention may be a method of producing a stable crystalline A / M / X material comprising formula [A] a [M] b [X] c A crystal of a compound having the formula [Z] on its entire surface p O q of the oxide coating.

[0171] in:

[0172] [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV;

[0173] p and q are positive numbers;

[0174] [A] comprises one or more A cations;

[0175] [M] comprises one or more M cations;

[0176] [X] comprises one or more X anions;

[0177] a is an integer from 1 to 6;

[0178] b is an integer from 1 to 6; and

[0179] c is an integer from 1 to 18,

[0180] Furthermore, the method comprises treating the following material with an oxide precursor containing element Z:

[0181] (a) an A precursor comprising an A cation; and

[0182] (b) M precursor including M cation.

[0183] Typically, the method is a method for producing a stable A / M / X material, wherein the stable A / M / X material is a polycrystalline material comprising a formula [A] a [M] b [X] c A crystal of a compound having the formula [Z] on its entire surface p O q of the oxide coating.

[0184] Thus, the method may be a method of producing a stable A / M / X material, the stable A / M / X material being a polycrystalline material comprising a formula [A] a [M] b [X] c A crystal of a compound having the formula [Z] on its entire surface p O q An oxide coating layer is provided, wherein at least a portion of the oxide coating layer is located at a crystal grain boundary.

[0185] The method may be a method of producing a stable A / M / X material, wherein the stable A / M / X material is a polycrystalline material comprising a polycrystalline material having the formula [A] a [M] b [X] c A plurality of crystallites and a plurality of grain boundaries between the crystallites of a compound, wherein the formula [Z] p O q The oxides are distributed along the grain boundaries, where

[0186] [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV;

[0187] p and q are positive numbers;

[0188] [A] comprises one or more A cations;

[0189] [M] comprises one or more M cations;

[0190] [X] comprises one or more X anions;

[0191] a is an integer from 1 to 6;

[0192] b is an integer from 1 to 6; and

[0193] c is an integer of 1-18.

[0194] Typically, the crystallites are substantially free of oxides. For example, the crystallites may contain less than 20 wt% oxygen, preferably less than 10 wt% oxygen or less than 5 wt% oxygen.

[0195] Oxide

[0196] The stable A / M / X materials of the present invention include oxides. The oxides can protect the A / M / X materials from environmental factors such as water and oxygen. In addition, the oxides can stabilize the crystals of the A / M / X materials and extend their photoluminescence lifetime. This indicates that the electron trap density within the material is reduced. The oxides can also generally increase the photoluminescence yield of the crystalline A / M / X materials.

[0197] In order to achieve the above-mentioned beneficial effects of photoluminescence yield and increased photoluminescence decay lifetime, the oxide should not absorb the light emitted by the A / M / X material itself. Therefore, the oxide has a band gap of at least 3 eV. 3 eV corresponds to a wavelength of about 413 nm. Therefore, the oxide of the present invention generally does not absorb light with a wavelength exceeding 413 nm. Preferably, the oxide has a band gap wider than 3.06 eV, which corresponds to a wavelength of about 405 nm. This is to enable the A / M / X material to be excited by GaN LED light, wherein the emission wavelength of the GaN LED may be as short as 405 nm, depending on the In doping of the emission layer in the GaN LED. Therefore, the band gap of the oxide is large enough that the oxide does not absorb any light (especially blue light) emitted by the A / M / X material or the light excitation source typically used to excite the A / M / X material.

[0198] This is particularly advantageous for the manufacture of optoelectronic devices such as LEDs or phosphors, where the device includes a light source that emits visible light such as blue light. The large band gap of the oxide also prevents the oxide from absorbing light emitted by the light source in the optoelectronic device.

[0199] Thus, the oxide has a band gap of at least 3 eV. Preferably, the oxide has a band gap of at least 3.5 eV or at least 4 eV.

[0200] Preferably, the oxide is transparent to visible light. This means that the oxide preferably does not absorb light with a wavelength of 420 nm to 700 nm. More preferably, the oxide does not absorb light with a wavelength of 400 to 750 nm. "Light" refers to electromagnetic radiation.

[0201] It is also preferred that the oxide is not reactive with water or oxygen. For example, the oxide may not react with water or oxygen at 300K.

[0202] The oxide is of formula [Z] p O q A compound of wherein [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV, and p and q are positive numbers.

[0203] The exact values ​​of p and q depend on the element or elements present in [Z]. The numbers p and q are both greater than zero. Generally, p and q are greater than 0 and less than 20. For example, p and q are typically greater than 0.01 and less than 20.

[0204] Typically, p is an integer. Additionally, typically, q is an integer. Typically, p and q are each 1 to 10. Thus, p may typically be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, and q may typically be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. Typically, p is 1 to 5. Additionally, typically, q is 0 to 5. For example, p and q may each be 1, 2, 3, 4 or 5. Preferably, p is 1 or 2. Also preferably, q is 1, 2, 3 or 4.

[0205] Oxide [Z] p O q A component [Z] is included, which may include one or more elements Z. For example, [Z] may include two, three or four elements Z. In a preferred embodiment, [Z] may consist of only one element Z.

[0206] Each element Z is an element capable of forming an oxide with a band gap of at least 3 eV. In general, each element Z is an element capable of forming a compound of the formula Z pp O qq An element of an oxide of , wherein pp and qq are positive integers. Typically, pp is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. Also, typically, qq is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. Typically, pp is 1 to 5. Also, typically, qq is 0 to 5. For example, pp and qq may each be 1, 2, 3, 4 or 5. Preferably, pp is 1 or 2. Also preferably, qq is 1, 2, 3 or 4.

[0207] Examples of suitable elements from which the element Z can be selected include Al, Si, Zr, Ga, Ba, Nb, Mg, Y, Ti, Ni, and Zn. Thus, in a typical embodiment, the oxide includes an element Z selected from Al, Si, Zr, Ga, Ba, Nb, Mg, Y, Ti, Ni, and Zn. In a preferred aspect of this embodiment in which [Z] includes two or more elements Z, each element Z is selected from Al, Si, Zr, Ga, Ba, Nb, Mg, Y, Ti, Ni, and Zn.

[0208] Preferably, the element Z may be selected from Al, Zr or Si. Therefore, in a preferred embodiment of the present invention, the oxide comprises an element Z selected from Al, Zr or Si. In a preferred aspect of this embodiment in which [Z] comprises two or three elements Z, each element Z is selected from Al, Zr or Si.

[0209] In a particularly preferred embodiment of the invention, [Z] consists of one element Z which is Al.

[0210] For example, the oxide of the present invention may include one or more of aluminum oxide (Al2O3), aluminum silicate (Al2SiO5), zirconium oxide (ZrO2), silicon dioxide (SiO2), or mixtures thereof.

[0211] Oxide Precursors

[0212] An oxide precursor is a substance that is capable of reacting with an oxidant to produce an oxide as defined herein. Thus, when an oxide (having the formula [Z] p O q ) includes two or more elements Z, the oxide precursor also includes the two or more elements Z. The oxide precursor includes the oxide [Z] p O q All elements Z in .

[0213] Thus, as used herein, the term "oxide precursor" may refer to a single compound comprising a single element Z; a single compound comprising multiple elements Z; or multiple compounds each comprising one or more elements Z. Thus, references herein to "oxide precursor" should be understood to refer to both single and multi-component species. To minimize complexity, it is preferred that the oxide precursor comprises a single compound containing all elements Z present in [Z].

[0214] The oxide precursor is typically reactive toward an oxidant. For example, the oxide precursor is typically reactive toward water and / or oxygen. It should be noted that "reactive toward water" means that the oxide precursor will react with H2O, whether the H2O is in liquid or gaseous form. In a preferred embodiment, the oxide precursor is reactive toward water. In a particularly preferred embodiment, the oxide precursor spontaneously reacts with water at 300K to form the oxide [Z] p O q .

[0215] Typically, the oxide precursor includes one or more elements Z and one or more labile ligands. "Labile" is used in the art as it is commonly understood. The skilled person can easily select one or more labile ligands suitable for use in the oxide precursor used in the method of the present invention. Suitable examples of labile ligands include labile organic ligands.

[0216] Specific examples of the labile organic ligand include alkyl ligands, alkenyl ligands, cycloalkyl ligands, alkoxy ligands, alkenyloxy ligands, and hydride ligands.

[0217] In some embodiments of the present method, the oxide precursor comprises one or more compounds of the formula ZRn A compound; wherein

[0218] n is a number from 1 to 6; and

[0219] R is each independently selected from optionally substituted C 1-10 Alkyl, C 2-10 Alkenyl, C 3-10 Cycloalkyl, C 1-10 Alkoxy, C 2-10 Alkenyloxy, hydride and halide; preferably selected from unsubstituted substituted C 1-10 Alkyl, C 2-10 Alkenyl, C 3-10 Cycloalkyl, C 1-10 Alkoxy, C 2-10 Alkenyloxy, hydride and halide.

[0220] Preferably, n is an integer from 1 to 6.

[0221] In a particularly preferred embodiment of the method, the oxide precursor comprises a compound of the formula ZR n One or more organometallic compounds, wherein n is a number (preferably an integer) from 1 to 5 (preferably 2 to 4), and R is each independently selected from unsubstituted C 1-6 Alkyl and C 1-6 In a particularly preferred aspect of this embodiment, R is methyl and n is 3.

[0222] Exemplary oxide precursors include triethylaluminum and trimethylaluminum, with trimethylaluminum being preferred.

[0223] Formula [A] a [M] b [X] c Compounds

[0224] The stable crystalline A / M / X materials of the present invention include the formula [A] a [M] b [X] c Formula [A] a [M] b [X] c The compound is typically crystalline. In the compound, [A] includes one or more A cations; [M] includes one or more M cations; [X] includes one or more X anions; a is an integer from 1 to 6; b is an integer from 1 to 6; and c is an integer from 1 to 18. a is typically an integer from 1 to 3, b is typically an integer from 1 to 3, and c is typically an integer from 1 to 8.

[0225] In embodiments where [A] comprises two or more A cations, each individual A cation may be represented herein as A I, A II , A III Similarly, when [M] includes two or more M cations, each individual M cation may be represented by M I 、M II 、M III When [X] includes two or more X anions, each individual X anion may be represented by X I , X II , X III wait.

[0226] Generally speaking, in formula [A] a [M] b [X] c Of the compounds:

[0227] [A] comprises one or more A cations, which may be selected from, for example, alkali metal cations or organic monovalent cations.

[0228] [M] includes one or more M cations selected from Pd 4+ , W 4+ 、Re 4+ , Os 4+ , Ir 4+ , Pt 4+ Sn 4+ , Pb 4+ ,Ge 4+ 、Te 4+ 、Bi 3+ , Sb 3+ Sn 2+ , Pb 2+ , Cu 2+ ,Ge 2+ and Ni 2+ The metal or metalloid cation in

[0229] [X] includes anions selected from halide anions (e.g. Cl - Br - and I - ), O 2– , S 2– 、Se 2– and Te 2– One or more X anions.

[0230] a is an integer from 1 to 3;

[0231] b is an integer from 1 to 3; and

[0232] c is an integer of 1-8.

[0233] Typically, the stable crystalline A / M / X material comprises a perovskite or a hexahalogenated metal salt. Preferably, the stable crystalline material comprises a perovskite. The stable crystalline material typically comprises a metal halide perovskite.

[0234] Typically, a = 1, b = 1 and c = 3. Thus, typically, crystalline A / M / X materials include perovskites of formula (I):

[0235] [A][M][X]3 (I)

[0236] wherein: [A] comprises one or more A cations, the A cations being monovalent cations; [M] comprises one or more M cations, the M cations being metal or metalloid divalent cations; and [X] comprises one or more anions, the anions being halide anions.

[0237] [A] includes one or more A cations, which may be organic and / or inorganic monovalent cations. When A is an organic monovalent cation, A is usually selected from C 1-10 Alkyl ammonium ion, C 2-10 Alkenyl ammonium ion, C 1-10 Alkyl iminium ion, C 3-10 Cycloalkylammonium ions and C 3-10 Cycloalkyl iminium ions, these groups are optionally selected from amino, C 1-6 Alkylamino, imino, C 1-6 Alkyl imine, C 1-6 Alkyl, C 2-6 Alkenyl, C 3-6 Cycloalkyl and C 6-12 The aromatic group is substituted by one or more substituents. For example, A can be selected from (CH3NH3) + 、(CH3CH2NH3) + 、(CH3CH2CH2NH3) + 、(N(CH3)4) + 、(H2N–C(H)=NH2) + and (H2N–C(CH3)=NH2) + When A is an inorganic monovalent cation, A is typically an alkali metal monovalent cation (i.e., a monovalent cation of a metal in Group 1 of the periodic table), such as Cs + or Rb + .

[0238] [A] generally comprises one, two or three A monovalent cations. Preferably, A comprises a cation selected from (CH3NH3) + 、(CH3CH2NH3) + 、(CH3CH2CH2NH3) + 、(N(CH3)4)+ 、(H2N-C(H)=NH2) + 、(H2N-C(CH3)=NH2) + , Cs + and Rb + Alternatively, [A] may include two cations selected from this group, such as Cs + and (H2N-C(CH3)=NH2) + , or for example Cs + and Rb + .

[0239] [M] includes one or more M cations, which are metal or metalloid divalent cations. For example, [M] may include M cations selected from the group consisting of: 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+ [M] generally includes one or more M cations, and these cations are generally 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 Pb 2+ or Sn 2+ In a particularly preferred embodiment, [M] is composed of Pb 2+ In another particularly preferred embodiment, [M] consists of Pb 2+ and Sn 2+ composition.

[0240] [X] includes one or more X anions. For example, [X] may include anions selected from F - Br - , Cl - and I- [X] generally includes one, two or three X anions, and these anions are generally selected from Br - , Cl - and I - .

[0241] In one embodiment, the perovskite is a perovskite of formula (IA):

[0242] [A I x A II 1-x ]MX3 (IA)

[0243] Among them, A I and A II As defined above for A, M and X are as defined above, and x is greater than 0 and less than 1. In a preferred embodiment, A I and A II Each selected from (CH3NH3) + 、(CH3CH2NH3) + 、(CH3CH2CH2NH3) + 、(N(CH3)4) + 、(H2N-C(H)=NH2) + 、(H2N-C(CH3)=NH2) + , Cs + and Rb + ; M is Pb 2+ , and X is selected from Br - , Cl - and I - For example, A I and A II They can be respectively (H2N-C(CH3)=NH2) + and Cs + Alternatively, they can be Cs + and Rb + .

[0244] In one embodiment, the perovskite is a perovskite compound of formula (IB):

[0245] AM[X I y X II 1-y ]3 (IA)

[0246] Where A and M are as defined above, where X I and X IIAs defined above for X, and y is greater than 0 and less than 1. In a preferred embodiment, A is selected from (CH3NH3) + 、(CH3CH2NH3) + 、(CH3CH2CH2NH3) + 、(N(CH3)4) + 、(H2N-C(H)=NH2) + 、(H2N-C(CH3)=NH2) + , Cs + and Rb + ; M is Pb 2+ , and X I and X II Each selected from Br - , Cl - and I - .

[0247] In a particularly preferred embodiment, the perovskite is a perovskite of formula (IC):

[0248] [A I x A II 1-x ]M[X I y X II 1-y ]3 (IC)

[0249] Among them, A I and A II As defined above for A, M as defined above, X I and X II As defined above for X, and x and y are both greater than 0 and less than 1. In a preferred embodiment, A I and A II Each selected from (CH3NH3) + 、(CH3CH2NH3) + 、(CH3CH2CH2NH3) + 、(N(CH3)4) + 、(H2N-C(H)=NH2) + 、(H2N-C(CH3)=NH2) + , Cs + and Rb + ; M is Pb 2+ , and X I and X II Each selected from Br - , Cl - and I - .

[0250] In a further preferred embodiment, the perovskite is a perovskite of formula (ID):

[0251] [A][M I z M II 1-z ][X]3 (ID)

[0252] Wherein, [A] and [X] are as defined herein, M I It is Pb 2+ , M II It's Sn 2+ , and z is greater than 0 and less than 1.

[0253] Generally speaking, in the above, x is 0.01 to 0.99. For example, x can be 0.05 to 0.95 or 0.1 to 0.9. Similarly, in the above, y is generally 0.01 to 0.99. For example, y can be 0.05 to 0.95 or 0.1 to 0.9. In an exemplary embodiment, x and y are both 0.1 to 0.9.

[0254] In an exemplary embodiment, formula [A] a [M] b [X] c The compound is selected from CsPbBr3, CsPbCl3, CsPbI3, CsPb(Br y Cl 1-y )3. CsPb(Br y I 1-y )3. CsPb(Cl y I 1-y )3、(Cs x R 1-x )PbBr3、(Cs x R 1-x )PbCl3、(Cs x R 1-x )PbI3、(Cs x R 1-x )Pb(Br y Cl 1-y )3、(Cs x R 1-x )Pb(Br y I 1-y )3 and (Cs x R 1-x )Pb(Cl y I 1-y)3, wherein x and y are both greater than 0 and less than 1. Preferably, in these embodiments, x is from 0.01 to 0.99, and y is from 0.01 to 0.99; more preferably, x is from 0.05 to 0.95, and y is from 0.05 to 0.95.

[0255] In one embodiment, a = 2, b = 1 and c = 4. In this embodiment, the stable crystalline A / M / X material comprises a compound of formula (II) ("2D layered perovskite"):

[0256] [A]2[M][X]4 (II)

[0257] wherein: [A] comprises one or more A cations, the A cations being monovalent cations; [M] comprises one or more M cations, the M cations being metal or metalloid divalent cations; and [X] comprises one or more X anions, the X anions being halide anions. In this embodiment, the A and M cations and the X anions are as defined above for the perovskite of formula (I).

[0258] In another embodiment, a = 2, b = 1 and c = 6. In this embodiment, the crystalline A / M / X material may in this case comprise a hexahalogenated metal salt of formula (III):

[0259] [A]2[M][X]6 (III)

[0260] wherein: [A] comprises one or more A cations, the A cations being monovalent cations; [M] comprises one or more M cations, the M cations being metal or metalloid tetravalent cations; and [X] comprises one or more X anions, the X anions being halide anions.

[0261] In a mixed monovalent cation hexahalometallate, [A] comprises at least two A cations that are monovalent cations; [M] comprises at least one M cation that is a metal or metalloid tetravalent cation (and typically [M] comprises a single M cation that is a metal or metalloid tetravalent cation); and [X] comprises at least one X anion that is a halide anion (and typically [X] comprises a single halide anion). In a mixed metal hexahalometallate, [A] comprises at least one monovalent cation (and typically [A] is a single monovalent cation); [M] comprises at least two metal or metalloid tetravalent cations (e.g., Ge 4+ and Sn 4+); and [X] comprises at least one halide anion (and typically [X] is a single halide anion). In a hexahalogenated metal salt of mixed halide ions, [A] comprises at least one monovalent cation (and typically [A] is a single monovalent cation); [M] comprises at least one metal or metalloid tetravalent cation (and typically [M] is a single metal tetravalent cation); and [X] comprises at least two halide anions, such as Br – and Cl - .

[0262] [A] may include at least one A monovalent cation selected from any suitable monovalent cation, such as those described above for perovskites. In the case of hexahalogenated metal salts, each A cation is typically selected from Li + 、Na + , K + , Rb + , Cs + NH4 + and a monovalent organic cation. A monovalent organic cation is an organic cation with a single positive charge, for example, it may have a molecular weight of no more than 500 g / mol. For example, [A] may be selected from Li + 、Na + , K + , Rb + , Cs + NH4 + and a single A cation of a monovalent organic cation. [A] preferably includes at least one A cation selected from Rb + , Cs + NH4 + and a monovalent cation among monovalent organic cations. For example, [A] may be selected from Li + 、Na + , K + , Rb + , Cs + and NH4 + In another embodiment, [A] can be at least one monovalent organic A cation. For example, [A] can be a single monovalent organic A cation.

[0263] Preferably, [A] comprises a single type of A cation, i.e. the hexahalogenated metal salt is a compound of formula A2[M][X]6. [A] may be selected from K + , Rb + , Cs + NH4 + 、(CH3NH3) + 、(CH3CH2NH3) + 、(CH3CH2CH2NH3)+ 、(N(CH3)4) + 、(N(CH2CH3)4) + 、(N(CH2CH2CH3)4) + 、(H2N-C(H)=NH2) + and (H2N-C(CH3)=NH2) + Preferably, [A] can be selected from Cs + NH4 + 、(CH3NH3) + 、(CH3CH2NH3) + 、(N(CH3)4) + 、(N(CH2CH3)4) + 、(H2N-C(H)=NH2) + and (H2N-C(CH3)=NH2) + In one embodiment, [A] is (CH3NH3) + In another embodiment, [A] is (H2N-C(H)=NH2) + In a further embodiment, [A] is ((NH2)2C(=NH)) + .

[0264] [M] may include one or more M cations selected from suitable metal or metalloid tetravalent cations. Metals include elements of Groups 3 to 12 of the periodic table and Ga, In, Tl, Sn, Pb, Bi, and Po. Metalloids include Si, Ge, As, Sb, and Te. For example, [M] may include at least one M cation selected from the following metal or metalloid tetravalent cations: Ti 4+ 、V 4+ , Mn 4+ , Fe 4+ 、Co 4+ 、Zr 4+ , Nb 4+ 、Mo 4+ 、Ru 4+ , Rh 4+ , Pd 4+ , Hf 4+ 、 4+ , W 4+ 、Re 4+ , Os 4+ , Ir 4+ , Pt 4+ Sn 4+ , Pb 4+ 、Po 4+ 、Si 4+ ,Ge4+ , and Te 4+ Typically, [M] comprises at least one selected from Pd 4+ , W 4+ 、Re 4+ , Os 4+ , Ir 4+ , Pt 4+ Sn 4+ , Pb 4+ ,Ge 4+ , and Te 4+ For example, [M] can be selected from Pd 4+ , W 4+ 、Re 4+ , Os 4+ , Ir 4+ , Pt 4+ Sn 4+ , Pb 4+ ,Ge 4+ , and Te 4+ A single metal or metalloid tetravalent cation in a.

[0265] Typically, [M] comprises at least one M cation selected from Sn 4+ 、Te 4+ ,Ge 4+ and Re 4+ In one embodiment, [M] comprises at least one M cation, which is selected from Pb 4 + Sn 4+ 、Te 4+ ,Ge 4+ and Re 4+ For example, [M] may include an M cation selected from Pb 4+ Sn 4+ 、Te 4+ and Ge 4+ Preferably, [M] comprises at least one metal or metalloid tetravalent cation selected from Sn 4+ 、Te 4+ and Ge 4+ At least one metal or metalloid tetravalent cation in the hexahalogenated metal salt. As described above, the hexahalogenated metal salt compound can be a mixed metal or a single metal hexahalogenated metal salt. Preferably, the hexahalogenated metal salt compound is a single metal hexahalogenated metal salt compound. More preferably, [M] is selected from Sn 4+ 、Te 4+ and Ge 4+[M] can be a single metal or metalloid tetravalent cation Te 4+ For example, [M] can be a single metal or metalloid tetravalent cation Ge 4+ Most preferably, [M] is a single metal or metalloid tetravalent cation Sn 4+ .

[0266] [X] may include at least one X anion which is a halide anion. Thus, [X] includes a - , Cl - Br - and I - At least one halide anion. Typically, [X] comprises a halide anion selected from Cl - Br - and I - At least one halide anion in the hexahalogenated metal salt compound. The hexahalogenated metal salt compound can be a mixed halide hexahalogenated metal salt or a monohalide hexahalogenated metal salt. If the hexahalogenated metal salt is a mixed halide, then [X] includes a compound selected from F - , Cl - Br - and I - In general, in the compound of mixed halide ions, [X] comprises a compound selected from F - , Cl - Br - and I - Two halide anions in .

[0267] Typically, [A] is a single monovalent cation and [M] is a single metal or metalloid tetravalent cation. Thus, the crystalline material may, for example, include a hexahalogenated metal salt compound of formula (IIIA).

[0268] A2M[X]6 (IIIA)

[0269] Wherein: A is a monovalent cation; M is a metal or metalloid tetravalent cation; and [X] is at least one halide anion. [X] can be selected from F - , Cl - Br - and I - One, two or three halide anions, and preferably selected from Cl - Br - and I - In formula (IIIA), [X] is preferably selected from Cl - Br - and I - One or two halide anions.

[0270] For example, the crystalline material can include or consist essentially of a hexahalometallate compound of formula (IIIB).

[0271] A2MX 6-y X′ y (IIIB)

[0272] Wherein: A is a monovalent cation (i.e., the second cation); M is a metal or metalloid tetravalent cation (i.e., the first cation); X and X' are each independently (different) halide anions (i.e., two second anions), and y is 0 to 6. When y is 0 or 6, the hexahalogenated metal salt compound is a monohalogenated ion compound. When y is 0.01 to 5.99, the compound is a mixed halide hexahalogenated metal salt compound. When the compound is a mixed halide ion compound, y can be 0.05 to 5.95. For example, y can be 1.00 to 5.00.

[0273] For example, the hexahalogenated metal salt compound may be A2SnF 6-y Cl y 、A2SnF 6-y Br y 、A2SnF 6-y I y 、A2SnCl 6- y Br y 、A2SnCl 6-y I y 、A2SnBr 6-y I y 、A2TeF 6-y Cl y 、A2TeF 6-y Br y 、A2TeF 6-y I y 、A2TeCl 6-y Br y 、A2TeCl 6-y I y 、A2TeBr 6-y I y 、A2GeF 6-y Cl y 、A2GeF 6-y Br y 、A2GeF 6-y I y 、A2GeCl 6-y Br y 、A2GeCl 6-y I y ,A2GeBr 6-y I y 、A2ReF6-y Cl y 、A2ReF 6-y Br y 、A2ReF 6-y I y 、A2ReCl 6-y Br y 、A2ReCl 6-y I y or A2ReBr 6-y I y , where: A is K + , Rb + , Cs + , (R 1 NH3) + ,(NR 2 4) + or (H2N-C(R 1 )=NH2, where R 1 is H, substituted or unsubstituted C 1-20 alkyl or substituted or unsubstituted aryl, and R 2 Is substituted or unsubstituted C 1-10 alkyl; and y is 0 to 6. Optionally, y is 0.01 to 5.99. If the hexahalogenated metal salt compound is a mixed halide ion compound, y is typically 1.00 to 5.00. A may be as defined above. For example, A may be Cs + NH4 + 、(CH3NH3) + 、(CH3CH2NH3) + 、(N(CH3)4) + 、(N(CH2CH3)4) + 、(H2N-C(H)=NH2) + or (H2N-C(CH3)=NH2) + , for example, Cs + NH4 + , or (CH3NH3) + .

[0274] The hexahalogenated metal salt compound may typically be A2SnF 6-y Cl y 、A2SnF 6-y Br y 、A2SnF 6-y I y 、A2SnCl 6-y Br y 、A2SnCl 6-y I y or A2SnBr 6-y Iy , where: A is K + , Rb + , Cs + , (R 1 NH3) + ,(NR 2 4) + or (H2N-C(R 1 )=NH2, or, A is as defined herein, wherein R 1 is H, substituted or unsubstituted C 1-20 an alkyl group or a substituted or unsubstituted aryl group, or R 2 Is substituted or unsubstituted C 1-10 an alkyl group; and y is 0 to 6.

[0275] In one embodiment, the hexahalogenated metal salt compound is A2GeF 6-y Cl y 、A2GeF 6-y Br y 、A2GeF 6-y I y 、A2GeCl 6-y Br y 、A2GeCl 6-y I y or A2GeBr 6-y I y , where: A is K + , Rb + , Cs + , (R 1 NH3) + ,(NR 2 4) + or (H2N-C(R 1 )=NH2, or, A is as defined herein, wherein R 1 is H, substituted or unsubstituted C 1-20 an alkyl group or a substituted or unsubstituted aryl group, and R 2 Is substituted or unsubstituted C 1-10 an alkyl group; and y is 0 to 6.

[0276] The hexahalogenated metal salt compound may be, for example, A2TeF 6-y Cl y 、A2TeF 6-y Br y 、A2TeF 6-y I y 、A2TeCl 6-y Br y 、A2TeCl 6-y Iy or A2TeBr 6-y I y , where: A is K + , Rb + , Cs + , (R 1 NH3) + ,(NR 2 4) + or (H2N-C(R 1 )=NH2, or, A is as defined herein, wherein R 1 is H, substituted or unsubstituted C 1-20 an alkyl group or a substituted or unsubstituted aryl group, and R 2 Is substituted or unsubstituted C 1-10 an alkyl group; and y is 0 to 6 or y is as defined herein.

[0277] Typically, y is between 1.50 and 2.50. For example, y may be between 1.80 and 2.20. This may occur if two equivalents of AX' and one equivalent of MX4 are used to prepare the compound, as described below.

[0278] In some embodiments, all anions are single species anions.Thus, the crystalline material may include or consist essentially of a hexahalometalate compound of formula (IIIC).

[0279] A2MX6 (IIIC)

[0280] wherein: A is a monovalent cation; M is a metal or metalloid tetravalent cation; and X is a halide anion. A, M and X may be as defined herein.

[0281] The hexahalogenated metal salt compound can be A2SnF6, A2SnCl6, A2SnBr6, A2SnI6, A2TeF6, A2TeCl6, A2TeBr6, A2TeI6, A2GeF6, A2GeCl6, A2GeBr6, A2GeI6, A2ReF6, A2ReCl6, A2ReBr6 or A2ReI6, wherein: A is K + , Rb + , Cs + , (R 1 NH3) + ,(NR 2 4) + or (H2N-C(R 1 )=NH2, where R 1 is H, substituted or unsubstituted C 1-20an alkyl group or a substituted or unsubstituted aryl group, and R 2 Is substituted or unsubstituted C 1-10 An alkyl group. A may be as defined herein. Preferably, the hexahalogenated metal salt compound is Cs2SnI6, Cs2SnBr6, Cs2SnBr 6-y I y 、Cs2SnCl 6-y I y 、Cs2SnCl 6-y Br y , (CH3NH3)2SnI6, (CH3NH3)2SnBr6, (CH3NH3)2SnBr 6-y I y 、(CH3NH3)2SnCl 6-y I y 、(CH3NH3)2SnCl 6-y Br y , (H2N-C(H)=NH2)2SnI6, (H2N-C(H)=NH2)2SnBr6, (H2N-C(H)=NH2)2SnBr 6-y I y 、(H2N-C(H)=NH2)2SnCl 6-y I y or (H2N-C(H)=NH2)2SnCl 6-y Br y , wherein y is 0.01 to 5.99. For example, the hexahalogenated metal salt compound may be (CH3NH3)2SnI6, (CH3NH3)2SnBr6, (CH3NH3)2SnCl6, (H2N-C(H)=NH2)2SnI6, (H2N-C(H)=NH2)2SnBr6 or (H2N-C(H)=NH2)2SnCl6. The hexahalogenated metal salt compound may be Cs2SnI6, Cs2SnBr6, Cs2SnCl 6-y Br y , (CH3NH3)2SnI6, (CH3NH3)2SnBr6 or (H2N-C(H)=NH2)2SnI6.

[0282] The crystalline A / M / X material may include a metal halide salt of bismuth or antimony. For example, the crystalline A / M / X material may include a metal halide salt compound containing: (i) one or more monovalent cations ([A]) or one or more divalent cations ([B]); (ii) one or more metal or metalloid trivalent cations ([M]); and (iii) one or more halide anions ([X]); the compound may be a compound of formula BBiX5, B2BiX7 or B3BiX9, wherein B is (H3NCH2NH3) 2+ 、(H3N(CH2)2NH3) 2+ 、(H3N(CH2)3NH3) 2+ 、(H3N(CH2)4NH3) 2+ 、(H3N(CH2)5NH3) 2+ 、(H3N(CH2)6NH3) 2+ 、(H3N(CH2)7NH3) 2+ 、(H3N(CH2)8NH3) 2+ or (H3N-C6H4-NH3) 2+ , and X is I - Br - or Cl - , preferably 1 - .

[0283] In another embodiment, the stable crystalline A / M / X material of the present invention may be a double perovskite. Such compounds are defined in WO 2017 / 037448, the entire contents of which are incorporated herein by reference. Typically, the compound is a double perovskite compound of formula (IV):

[0284] [A]2[B + ][B 3+ ][X]6 (IV);

[0285] wherein: [A] comprises one or more A cations, the A cation being a monovalent cation as defined herein; [B + ] and [B 3+ ] is equivalent to [M], wherein M includes one or more M cations that are monovalent cations and one or more M cations that are trivalent cations; and [X] includes one or more X anions that are halide anions.

[0286] Included in [B + ] wherein the one or more M cations which are monovalent cations are generally selected from metal and metalloid monovalent cations. Preferably, the one or more M cations which are monovalent cations are selected from Li + 、Na + , K + , Rb+ , Cs + , Cu + 、Ag + 、Au + and Hg + More preferably, the one or more M cations which are monovalent cations are selected from Cu + 、Ag + and Au + Most preferably, the one or more M cations which are monovalent cations are selected from Ag + and Au + For example, [B + ] can be a monovalent cation Ag + , or [B + ] can be a monovalent cation Au + .

[0287] Included in [B 3+ ] wherein the one or more M cations which are trivalent cations are typically selected from metal and metalloid trivalent cations. Preferably, the one or more M cations which are trivalent cations are selected from 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+ More preferably, the one or more M cations which are trivalent cations are selected from Bi 3 + and Sb 3+ For example, [B 3+ ] can be a trivalent cation Bi 3+ , or [B 3+ ] can be a trivalent cation Sb 3+ Compared to heavy metals such as lead, bismuth has relatively low toxicity.

[0288] In some embodiments, it is one or more M cations of a monovalent cation (in [B + ]) is selected from Cu + 、Ag + and Au + , and one or more M cations which are trivalent cations (in [B 3+ ]) Selected from Bi 3+ and Sb 3+ .

[0289] Typically, when the compound is a double perovskite, it is a compound of formula (IVa):

[0290] A2B + B 3+ [X]6 (IVa);

[0291] Wherein: A cation is as defined herein; B + is an M cation, which is a monovalent cation as defined herein; 3+ is an M cation, which is a trivalent cation as defined herein; [X] comprises one or more X anions, which are halide anions, such as two or more halide anions, preferably a single halide anion.

[0292] In another embodiment, the compound may be a layered double perovskite compound of formula (V):

[0293] [A]4[B + ][B 3+ ][X]8 (V);

[0294] Where: [A], [B + ]、[B 3+ ] and [X] are as defined above. In this embodiment, the layered double perovskite compound is typically a double perovskite compound of formula (Va):

[0295] A4B + B 3+ [X]8 (Va);

[0296] Wherein: A cation is as defined herein; B + is an M cation, which is a monovalent cation as defined herein; 3+ is an M cation, which is a trivalent cation as defined herein; [X] comprises one or more X anions, which are halide anions, such as two or more halide anions, preferably a single halide anion.

[0297] Therefore, in general, in formula [A] a [M] b [X] c In the compound, [A] includes one or more A cations; [M] includes one or more M cations, and [X] includes one or more anions.

[0298] Typically, the A cations are each selected from alkali metal cations, C 1-10 Alkyl ammonium ion, C 2-10 Alkenyl ammonium ion, C 1-10 Alkyl iminium ion, C 3-10 Cycloalkylammonium ions and C 3-10Cycloalkyliminium ion, wherein the above C 1-10 Alkyl ammonium ion, C 2-10 Alkenyl ammonium ion, C 1-10 Alkyl iminium ion, C 3-10 Cycloalkylammonium ions and C 3-10 The cycloalkyliminium ion is optionally selected from amino, C 1-6 Alkylamino, imino, C 1-6 Alkyl imine, C 1-6 Alkyl, C 2-6 Alkenyl, C 3-6 Cycloalkyl and C 6-12 Preferably, each of the A cations is selected from Cs + , Rb + [A] is a cation of one or more A cations. ...

[0299] Typically, the M cations are each selected from metal or metalloid cations, preferably from Li + 、Na + , K + , Rb + , Cs + , Cu + 、Ag + 、Au + , Hg + , 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+ 、Bi 3+ , Sb 3+ Cr 3+ , Fe 3+ 、Co 3+ , Ga 3+ 、As 3+ 、Ru3+ , Rh 3+ 、In 3+ , Ir 3+ and Au 3+ One or more of, preferably selected from Cu + 、Ag + 、Au + Sn 2+ , Pb 2+ , Cu 2+ ,Ge 2+ 、Ni 2+ 、Bi 3+ and Sb 3+ ; Pb is particularly preferred 2+ For example, preferably, each M cation is a metal or metalloid divalent cation.

[0300] Typically, the X anions are each selected from F - , Cl - Br - or I - , preferably Cl - or Br - .

[0301] It is generally preferred that one or more A cations are monovalent cations and one or more M cations are divalent cations. It is particularly preferred that the formula [A] a [M] b [X] c The compound is a compound of formula [A][M][X]3, wherein each A cation is a monovalent cation and each M cation is a metal or metalloid divalent cation.

[0302] In a preferred embodiment, [A] comprises two or more different A cations. In a particularly preferred aspect of this embodiment, formula [A] a [M] b [X] c The compounds are perovskites of formula [A][M][X] 3. These "mixed cation perovskites" are demonstrated in the Examples section to have unexpectedly good photoluminescent properties, particularly in the blue region of the spectrum.

[0303] In another preferred embodiment, [X] comprises two or more different X anions. In particularly preferred aspects of these embodiments, formula [A] a [M] b [X] cThe compound is a perovskite of formula [A][M][X]. These "mixed halide perovskites" have been shown to degrade when stabilized using previous stabilization techniques, usually due to halide segregation. The stable crystalline A / M / X materials of the present invention, including oxides, do not have these difficulties.

[0304] In a preferred embodiment, the material is a "blue emitter". This refers to a material of formula [A] a [M] b [X] c The compound of formula [A] can emit blue light after being excited by electric energy or irradiated with blue light, purple light or ultraviolet light (e.g., light with a wavelength of 500 nm or less). a [M] b [X] c The compound is capable of emitting light at a wavelength of 450 to 500 nm, for example 455 to 495 nm, preferably 460 to 490 nm.

[0305] A precursor and M precursor

[0306] The A precursor is a substance that is capable of reacting with the M precursor and the oxide precursor to produce a stable crystalline A / M / X material as defined herein. Thus, when the formula [A] a [M] b [X] c When the compound comprises two or more A cations, the A precursor also comprises the two or more A cations. The A precursor comprises a compound present in the formula [A] a [M] b [X] c [A] contains all cations A in the compound. Thus, in this document, the term "A precursor" may refer to a single compound comprising a single A cation; a single compound comprising multiple A cations; or multiple compounds each comprising one or more A cations. Thus, reference to "A precursor" herein should be understood to refer to both a single substance and a multi-component substance. To minimize complexity, it is preferred that the A precursor comprises a single compound containing all A cations present in [A].

[0307] The M precursor is a substance that is capable of reacting with the A precursor and the oxide precursor to produce a stable crystalline A / M / X material as defined herein. Thus, when the formula [A] a [M] b [X] c When the compound includes two or more M cations, the M precursor also includes the two or more M cations. The M precursor includes a compound present in the formula [A] a [M] b [X] c[M] contains all cations M in the compound. Thus, in this article, the term "M precursor" can refer to a single compound including a single M cation; a single compound including multiple M cations; or multiple compounds each including one or more M cations. Therefore, the "M precursor" mentioned herein should be understood to refer to both a single substance and a multi-component substance. In order to minimize complexity, it is preferred that the M precursor includes a single compound containing all M cations present in [M].

[0308] The stable crystalline A / M / X materials of the present invention include component [X], which includes one or more anions X. Therefore, the method requires a source of these anions. In some embodiments, the method involves an X precursor. The X precursor is a substance that can react with the A precursor, the M precursor and the oxide precursor to produce a stable crystalline A / M / X material as defined herein. The X precursor may include a compound present in the formula [A] a [M] b [X] c Some or all of the X anions in the compound.

[0309] In such an embodiment, the method of the present invention comprises treating the A precursor, the M precursor, and the X precursor with an oxide precursor.

[0310] However, more typically, the source of X anions in the method of the present invention is one or more of an A precursor, an M precursor, and an oxide precursor. That is, typically one or more of an A precursor, an M precursor, and an oxide precursor include the X anions required to form a stable crystalline A / M / X material. Of course, additional X precursors may also be involved in the method of the present invention.

[0311] In a preferred aspect of this embodiment of the invention, one of the A precursor or the M precursor, or both the A precursor and the M precursor, comprises one or more X anions. In this embodiment, the method of the invention comprises treating with an oxide precursor comprising element Z:

[0312] (a) an A precursor comprising an A cation and optionally an X anion; and

[0313] (b) an M precursor comprising an M cation and optionally an X anion.

[0314] In a preferred aspect of this embodiment, the A precursor and the M precursor together include all of the X anions required to provide a stable crystalline A / M / X product.

[0315] Thus, preferably, the A precursor comprises one or more salts of each A cation present in [A], wherein the salts comprise one or more X anions present in [X]. Similarly, preferably, the M precursor comprises one or more salts of each M cation present in [M], wherein the salts comprise one or more X anions present in [X]. It is particularly preferred that the A precursor and the M precursor together comprise all X anions present in [X].

[0316] Typically, [X] includes one or more X anions, which are halide anions. Preferably, [X] includes one or more X anions, all of which are halide anions. Therefore, it is preferred that the A precursor includes a halide salt of one or more A cations contained in a stable crystalline A / M / X material. For example, it is preferred that the A precursor is an A cation or a halide salt of each A cation. Similarly, it is preferred that the M precursor includes a halide salt of one or more M cations contained in a stable crystalline A / M / X material. For example, the M precursor can be an M cation or a halide salt of each M cation.

[0317] In a particularly preferred embodiment, the A precursor consists of one or more halide salts of the A cations or each A cation in [A], and the M precursor consists of one or more halide salts of the M cations or each M cation in [M].

[0318] Stable crystalline A / M / X materials

[0319] The stable crystalline A / M / X material of the present invention, also referred to as the "product" of the present invention, is as defined herein. The stable crystalline A / M / X material can be obtained by the method of the present invention. Therefore, the following definition of the stable crystalline A / M / X material of the present invention also applies to the product of the method of the present invention described herein. Similarly, all aspects of the method of the present invention described above also apply to the product of the present invention.

[0320] Thus, in some embodiments, the present invention provides a product obtained or obtainable by a method of the present invention as defined herein.

[0321] The products of the present invention are advantageous because the oxides can stabilize the crystalline A / M / X materials. The advantages of the products of the present invention are demonstrated in the data provided herein.

[0322] First, for comparison, Figure 1 and Figure 2 Common stability problems of A / M / X materials obtained by conventional methods are illustrated. Figure 1Normalized photoluminescence intensity of perovskite (CsPbBr3) nanocrystals as formed and after 12 hours is shown. CsPbBr3 nanocrystals are coated with various polymeric stabilizing coatings. Figure 1 (a) shows the photoluminescence of nanocrystals coated with the polymers polyvinyl butyral (PVB, squares) and ethylene vinyl acetate (EVA, circles). Figure 1 (b) shows the photoluminescence properties of nanocrystals dispersed in polymethyl methacrylate (squares) and polystyrene (circles). In all cases, despite the plastic protective layer, the photoluminescence intensity of the perovskite drops to a fraction of its original intensity after only 12 hours. Figure 1 In (a), there is absolutely no visible photoluminescence after 12 h.

[0323] Figure 2 It is shown that the Figure 1 The poor stability of the nanocrystals is shown in Figure 2. Thin films of the perovskite CsPbBr3 initially showed a small increase in photoluminescence, but after about 150 hours, its photoluminescence quantum yield (PLQY) dropped to about half of its initial value and well below half of its maximum value. Figure 1 The lifetimes of nanocrystals observed in the study are much longer, but still insufficient for use in optoelectronic devices, which are typically expected to last for months or years.

[0324] In contrast, the excellent photoluminescence performance of the product of the present invention is Figure 3 , Figure 4 and Figure 5 Shown in.

[0325] Figure 3 It is shown that the presence of a stable oxide in the stable crystalline A / M / X material of the present invention does not significantly change the photoluminescence spectrum of the A / M / X material encapsulated therein. Figure 3 The stable A / M / X material is prepared by the method described in the Examples section below, wherein the method comprises treating a first solution with a second solution, wherein the first solution comprises an A precursor (a halide of Cs), an M precursor (a halide of Pb), and a first solvent; and the second solution comprises an oxide precursor (trimethylaluminum, "TMA") and a second solvent. Al 3+ Precursor and Pb 2+ The ratio of the precursors (in mole percent, mol%) ranged from 0 (no TMA) to 6.4 (100 mol of Pb in the precursor solution). 2+ Contains 6.4 mol Al 3+ ).from Figure 3 It can be seen that the presence of TMA (which provides stable alumina in the product) does not significantly shift the absorption peak (see Figure 3 (a)) or emission peak (see Figure 3 (b)). Figure 3 The similarity in the absorption peak positions can be seen most clearly in (c), where the normalized photoluminescence spectra overlap. Thus, in general, the presence of a stable oxide maintains the peak positions in both the photoluminescence and absorption spectra ("peak position" means maximum photoluminescence wavelength / maximum absorption wavelength, respectively). These peak positions and PLQYs are summarized in Table 1 below.

[0326]

[0327] Table 1

[0328] The peak position shifted by 2 nm at most.

[0329] In addition, the stabilized oxide has a further beneficial effect: it can increase the photoluminescence intensity. Figure 3 Comparing the spectrum of CsPbBr3 without oxide (squares) in (b) with the spectrum of the stabilized CsPbBr3 containing the maximum amount of oxide (diamonds), it can be clearly seen that the maximum photoluminescence intensity of the latter is about 6 times higher than the photoluminescence intensity of the unstabilized CsPbBr3 at the corresponding wavelength. In addition, Table 1 shows that the PLQY (photoluminescence quantum yield) in all cases is at least 3 times greater than the PLQY of the unstabilized perovskite.

[0330] Therefore, in a preferred embodiment of the present invention, the stable crystalline A / M / X material has a photoluminescence intensity greater than or equal to the corresponding formula [A] a [M] b [X] c For example, a stable crystalline A / M / X material has a PLQY greater than or equal to the corresponding formula [A] a [M] b [X] c In particular, the PLQE of a stable crystalline A / M / X material is greater than or equal to the corresponding formula [A] a [M] b [X] c The PLQE of a crystalline compound of . The photoluminescence intensity, PLQE and PLQY can be measured using standard techniques. PLQY stands for photoluminescence quantum yield, which can also be called PLQE (photoluminescence quantum efficiency).

[0331] Stable oxides not only have a favorable effect on the photoluminescence intensity, but also greatly extend the time during which a high PLQY is observed. Figure 1 and Figure 2As shown in Figure 2, the PLQY of the non-stabilized CsPbBr3 perovskite is much lower than its initial value within 12 h for nanocrystals and 125 h for thin films. Figure 4 It can be seen that the stable A / M / X materials of the present invention (using stable CsPbBr3 as an example) have longer lifetimes before they decay in this way. Figure 4 (a) shows that, if Figure 3 Discussion The as-prepared CsPbBr3 films maintained a PLQY greater than or equal to its initial value for at least 200 h. Figure 5 It was confirmed that the film actually maintained a PLQY greater than its initial value for more than 200 hours: the film was tested for up to 6000 hours with no signs of dropping to or below its initial value. In contrast, a corresponding film without a stabilizing oxide dropped below its initial value within 125 hours. Such a long lifetime demonstrates the film's exceptional stability.

[0332] Figure 4 (b) It is confirmed that the photoluminescence spectrum of the stable A / M / X material of the present invention shifts very little during this period; only about 2 nm after 152 hours.

[0333] Thus, in particularly preferred embodiments of the present invention, the photoluminescence intensity of the stable A / M / X material of the present invention is approximately equal to or greater than its initial value for at least 100 hours, such as for at least 150 hours or at least 500 hours; preferably for at least 1000 hours. In one aspect of this embodiment, the PLQY of the stable A / M / X material of the present invention is equal to or greater than its initial value for at least 100 hours, such as for at least 150 hours or at least 500 hours; preferably for at least 1000 hours. In another aspect of this embodiment, the PLQE of the stable A / M / X material of the present invention is equal to or greater than its initial value for at least 100 hours, such as for at least 150 hours or at least 500 hours; preferably for at least 1000 hours.

[0334] In another preferred embodiment of the present invention, the peak wavelength of the photoluminescence spectrum of the stable A / M / X material of the present invention does not differ from its initial value by more than 5 nm, preferably by less than 3 nm, and more preferably by less than 1 nm after 100 hours, such as after 150 or 500 hours, and preferably after 1000 hours.

[0335] "Initial value" refers to the value of the parameter measured when the material is formed, for example, within 1 hour or within 30 minutes after the material is prepared.

[0336] The advantages of the present invention are also significant, wherein the stable A / M / X materials of the present invention are prepared using the antisolvents described herein. In this embodiment, the stable A / M / X materials are prepared by the "quenching" method described in the Examples section below, wherein the method comprises treating a first solution with a second solution, wherein the first solution comprises an A precursor (halide of Cs), an M precursor (halide of Pb), and a first solvent; and the second solution comprises an oxide precursor (trimethylaluminum, "TMA") and an antisolvent. The concentration of TMA present in the antisolvent varies between 0 and 100 mM.

[0337] Figure 7 and Figure 8 The properties of thin films of stable A / M / X materials of the present invention produced using an antisolvent as described in the previous paragraph are shown. The oxide in this example is Al2O3, formula [A] a [M] b [X] c The compound is a mixed halide perovskite: CsPb(Br 0.7 Cl 0.3 )3. Figure 6 (a) shows the absorption spectrum, Figure 6 (b) shows the normalized photoluminescence intensity of this material according to the invention. Figure 3-Figure 5 As with the CsPbBr3 material, it can be seen that the photoluminescence spectrum is not shifted by the presence of the stable oxide. The peak in the absorption spectrum produced in the absence of the oxide precursor (where the concentration of TMA is zero) is in almost exactly the same position as the peak in the absorption spectrum produced when the concentration of TMA in the antisolvent is 100mM. So, again, the presence of the oxide does not shift either the photoluminescence spectrum or the absorption spectrum.

[0338] Figure 7 The PLQY, PL peak position (ie, peak value of the photoluminescence spectrum) and FWHM of absorption of each film shown in are shown in Table 2 below.

[0339]

[0340] Table 2

[0341] Table 2 shows that the peak position shifts by only 4 nm at most relative to the peak position in the absence of oxide. Table 2 also shows that the same advantageous photoluminescence increase, ie, PLQY increase, is also evident in the process using the antisolvent technique.

[0342] Figure 7 The advantageously extended lifetime of the stable crystalline A / M / X materials according to the present invention is shown. In the absence of a stable oxide, CsPb(Br0.7 Cl 0.3 )3 film significantly decreased in 150 hours. In contrast, the PLQY of the film including CsPb(Br 0.7 Cl 0.3 The PLQY of the stabilized crystalline A / M / X materials of )3 and alumina after 150 hours has a value very close to its initial value. No significant loss of PLQY is observed for the films of the invention over the entire 300-hour experimental period. In contrast, the PLQY of the non-stabilized CsPb(Br) 0.7 Cl 0.3 )3's PLQY drops to almost 0.

[0343] Thus, in a preferred embodiment of the present invention, the photoluminescence intensity of the stable A / M / X material of the present invention measured about 100 hours after its formation, such as at least 150 hours or at least 500 hours after its formation, preferably at least 1000 hours after its formation is about equal to or greater than its initial value. In one aspect of this embodiment, the PLQY of the stable A / M / X material measured about 100 hours after its formation, such as at least 150 hours or at least 500 hours after its formation, preferably at least 1000 hours after its formation is about equal to or greater than its initial value. In another aspect of this embodiment, the PLQE of the stable A / M / X material of the present invention measured about 100 hours after its formation, such as at least 150 hours or at least 500 hours after its formation, preferably at least 1000 hours after its formation is about equal to or greater than its initial value.

[0344] Without wishing to be bound by theory, it is speculated that the above advantages of the present invention may be due, at least in part, to the contact of the oxide precursor with the precursor of the A / M / X material, thereby contacting the oxide with the precursor of the formula [A] a [M] b [X] c Experiments were conducted in which a stable CsPb(Br 0.7 Cl 0.3 )3 thin film. In one experiment, an antisolvent containing TMA was added to the Cs and Pb precursors according to the present invention. In another experiment, in CsPb (Br 0.7 Cl 0.3 )3 After crystallization, an antisolvent containing TMA was added. The normalized spectrum of the obtained film is as follows Figure 8As shown, it can be seen that the photoluminescence peaks are very similar. However, when the photoluminescence intensity is measured, it can be seen that the method of the present invention can produce a product with significantly stronger photoluminescence intensity. These results are shown in Table 3 below. In the case of adding the oxide precursor TMA during the formation of the stable crystalline A / M / X material of the present invention (indicated as "during" in the table), a PLQY of 9.52 was observed. In contrast, in CsPb(Br 0.7 Cl 0.3 )3 In the case of adding TMA and antisolvent after crystallization, the observed PLQY was only 5.11.

[0345]

[0346] Table 3

[0347] The stable crystalline A / M / X materials of the present invention include the formula [A] a [M] b [X] c A crystal of a compound having the formula [Z] on its entire surface p O q An oxide coating layer, wherein:

[0348] [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV;

[0349] p and q are positive numbers;

[0350] [A] comprises one or more A cations;

[0351] [M] comprises one or more M cations;

[0352] [X] comprises one or more X anions;

[0353] a is an integer from 1 to 6;

[0354] b is an integer from 1 to 6; and

[0355] c is an integer of 1-18.

[0356] [A] a [M] b [X] c , [Z] p O q , [A], A, [M], M, [X], X, [Z], Z, a, b, c, p and q are as defined herein.

[0357] In the stable crystalline A / M / X material of the present invention, it is convenient to define the amount of oxide present in terms of the molar ratio of [Z] to [M]. The molar ratio of [Z]:[M] is typically from 1:1 to 1:10000. The molar ratio of [Z]:[M] is preferably from 1:2 to 1:1000, for example from 1:5 to 1:500; particularly preferably from 1:5 to 1:100.

[0358] The stable crystalline A / M / X materials of the present invention are crystalline. The term "crystalline" as used herein encompasses single crystal and polycrystalline materials. A crystalline compound is a compound having an extended three-dimensional crystal structure. Crystalline compounds are generally in the form of crystals, or, in the case of polycrystalline compounds, in the form of crystallites (i.e., a plurality of crystals having a particle size less than or equal to 1 μm). Typically, the crystals form layers together. The crystals of a crystalline material can be of any size. When the crystals of the compounds of the present invention are in the form of crystals (rather than polycrystalline forms), they typically have a minimum dimension of not less than 1 nm and a maximum dimension of no more than 100 microns (μm). When crystals have one or more dimensions in the range of 1 nm to 1000 nm, they can be referred to as nanocrystals.

[0359] The stable crystalline A / M / X materials of the present invention include the formula [A] a [M] b [X] c The crystals of the compound, which form a compound having the formula [Z] p O q Therefore, the first crystallization [A] a [M] b [X] c material, and then depositing on its exposed surface a substance of formula [Z] p O q Unlike the method of forming an oxide of the present invention, the compound of the present invention includes a crystal having an oxide coating layer on the entire surface of the crystal. "On the entire surface" means that the entire surface of the crystal is coated with at least one atom thick of the formula [Z] p O q oxide layer.

[0360] Of course, the stable crystalline A / M / X materials of the present invention are not completely homogeneous. In the bulk of the material, there may be some crystals that do not have an oxide coating over the entire surface. However, in general, the stable crystalline A / M / X materials of the present invention include the formula [A] a [M] b [X] c A plurality of crystals of a compound of the invention, wherein each crystal has a structure of formula [Z] on its entire surface p O qIn a preferred embodiment, the stable crystalline A / M / X material of the present invention has the formula [A] a [M] b [X] c At least half of the crystals of the compound have the formula [Z] on their entire surface p O q Preferably, the stable crystalline A / M / X material of the present invention has the formula [A] a [M] b [X] c At least three quarters, more preferably at least 90%, of the crystals of the compound of formula [Z] have on their entire surface p O q of the oxide coating.

[0361] In a preferred embodiment, the stable crystalline A / M / X material of the present invention is a polycrystalline material. "Polycrystalline material" herein refers to a crystalline material including grain boundaries between crystallites. A crystalline material that is not a polycrystalline material is a material that includes one or more crystals without grain boundaries. Grain boundaries refer to planar defects that separate regions of different crystal orientations (i.e., grains) in a crystalline solid. Therefore, a grain boundary refers to the interface between two adjacent grains or crystallites in a crystalline material. Such a polycrystalline material can have particularly advantageous optical properties and improved stability. In the case of a polycrystalline material, reference to a crystal, such as "a crystal with a coating", should be understood as a crystallite, such as "a crystal with a coating".

[0362] When the product includes a polycrystalline material containing crystallites, the crystallites include A / M / X material. The crystallites (excluding the oxide coating) are typically substantially free of oxides. For example, the crystallites typically include 20 wt% or less oxygen, preferably 10 wt% or less oxygen; for example, 5 wt% or less oxygen or 1 wt% or less oxygen. The crystallites may include 0.1 wt% or less oxygen. In addition, the crystallites typically include 20 wt% or less [Z], preferably 10 wt% or less [Z]; for example, 5 wt% or less [Z], or 1 wt% or less [Z]. The crystallites may include 0.1 wt% or less [Z].

[0363] Thus, in a preferred embodiment, the stable crystalline A / M / X material of the present invention is a material comprising said crystals having the formula [Z] p O q A polycrystalline material having an oxide coating layer (Z) wherein at least a portion of the oxide coating layer is located at a crystal grain boundary. Because an oxide precursor is present during the formation of the polycrystalline material, a location of the oxide coating layer is present at the crystal grain boundary. When all faces of the crystal are surrounded by grain boundaries, the formula [Z] p Oq The entirety of the oxide coating will be located at these grain boundaries.

[0364] Thus, the product may include a polycrystalline material comprising a polycrystalline material having, over the entire surface of the crystal, a structure having the formula [Z] p O q A crystal having an oxide coating, wherein the crystal is substantially free of oxide and at least a portion of the oxide coating is located at a crystal grain boundary.

[0365] Thus, the product may include a polycrystalline material comprising a crystal having the formula [Z] on the entire surface of each crystal. p O q A plurality of crystals having an oxide coating, wherein the crystals are substantially free of oxide and at least a portion of the oxide coating is located at crystal grain boundaries.

[0366] The stable A / M / X material is a polycrystalline material, wherein the polycrystalline material comprises a material having the formula [A] a [M] b [X] c A plurality of crystallites of a compound and a plurality of grain boundaries between the crystallites, wherein the formula [Z] p O q The oxides are distributed along the grain boundaries, where

[0367] [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV;

[0368] p and q are positive numbers;

[0369] [A] comprises one or more A cations;

[0370] [M] comprises one or more M cations;

[0371] [X] comprises one or more X anions;

[0372] a is an integer from 1 to 6;

[0373] b is an integer from 1 to 6; and

[0374] c is an integer of 1-18.

[0375] Typically, the crystallites are substantially free of oxides. For example, the crystallites may contain less than 20 wt% oxygen, preferably less than 10 wt% oxygen or less than 5 wt% oxygen. In addition, the crystallites typically include 20 wt% or less [Z], preferably 10 wt% or less [Z]; for example 5 wt% or less [Z], or 1 wt% or less [Z]. The crystallites may include 0.1 wt% or less [Z].

[0376] Preferably, the stable A / M / X material which is a polycrystalline material comprises the formula [A] a [M] b [X] c A crystal of a compound having the formula [Z] on its entire surface p O q an oxide coating as described herein.

[0377] As is the case with crystals of non-polycrystalline materials, the distribution of the oxide coating varies throughout the bulk of the stable polycrystalline A / M / X material. Typically, where the stable crystalline A / M / X material is a polycrystalline material, the material comprises the formula [A] a [M] b [X] c A plurality of crystallites of a compound of formula [Z], each crystallite having on its entire surface p O q In a preferred embodiment, the stable polycrystalline A / M / X material of the present invention has the formula [A] a [M] b [X] c At least half of the crystallites of the compound have on their entire surface the formula [Z] p O q Preferably, the stable polycrystalline A / M / X material of the present invention has the formula [A] a [M] b [X] c At least three quarters, more preferably at least 90%, of the crystallites of the compound of formula [Z] have on their entire surface p O q In a specific embodiment, the present invention provides a stable crystalline A / M / X material, which is a polycrystalline material, wherein each crystal (ie, each crystallite) in the polycrystalline material has the coating on its entire surface.

[0378] Whether a polycrystalline material is formed (relative to a crystalline material without grain boundaries) can be controlled by changing the crystallization conditions according to techniques well known in the art. The average crystal size or the size of the crystallites in a polycrystalline material can also be changed by changing the crystallization conditions according to techniques well known in the art.

[0379] The stable crystalline material of the present invention generally includes crystals with a diameter of 1 nm to 5 μm. Therefore, a crystal having an oxide coating on its entire surface generally has a diameter of 1 nm to 5 μm. "Diameter" refers to the diameter of the smallest sphere that can be completely contained in the crystal. Of course, as in general, in the case where the crystalline material is a polycrystalline material, the term "crystal" should be understood to refer to "crystal".

[0380] More generally, the stable crystalline material of the present invention comprises crystals having a diameter of 10 nm to 1 μm. Thus, the crystals having an oxide coating on their entire surface generally have a diameter of 10 nm to 1 μm. In one embodiment, the stable crystalline material of the present invention comprises crystals having a diameter of at least 50 nm, or at least 100 nm. In this embodiment, the diameter of the crystals having an oxide coating on their entire surface is at least 50 nm, preferably at least 100 nm.

[0381] The oxide capping layer itself may have a wide range of thicknesses. The "thickness" of an oxide capping layer refers to the average height measured perpendicular to the crystal plane in which it lies.

[0382] The oxide coating is at least one atom thick. The maximum thickness of the oxide coating is not particularly limited. In general, the thickness of the oxide coating is less than the diameter of the crystal, especially when the crystal diameter is 50 nm or more. The thickness usually varies with the amount of oxide precursor used in the process of forming a stable crystalline A / M / X material. However, after forming a stable crystalline A / M / X material according to the method described herein, further oxide deposition can be performed on the stable crystalline material to form a thicker oxide layer.

[0383] Thus, typically, in the stable crystalline A / M / X materials of the present invention, the oxide coating has a minimum thickness of 0.1 nm. The oxide coating may, for example, be at least 1 nm thick or at least 2 nm thick, such as at least 5 nm thick. The oxide coating is typically 0.5 nm to 500 nm thick. For example, the oxide coating may be 1 nm to 100 nm thick, such as 2 nm to 50 nm thick.

[0384] The stable crystalline A / M / X materials of the present invention include the formula [A] a [M] b [X] c Compounds of formula [Z] p O q However, it may include various other substances. For example, formula [A] a [M] b [X] c Compounds of formula [Z] p O q The oxide may include one or more impurities. Such impurities may include, for example, residual solvent molecules, residual A precursors, residual M precursors, residual oxide precursors, residual solvent molecules, or residual water.

[0385] In a preferred embodiment, formula [A] a [M]b [X] c The compound includes at least one element Z as an impurity. Since in the formation of formula [A] a [M] b [X] c The element Z is present in the process of the compound, so this impurity will be produced.

[0386] Generally, in order to avoid excessive degradation of the optical properties of the materials of the present invention, it is necessary to avoid large amounts of impurities. Therefore, in a preferred embodiment, the stable A / M / X material is essentially composed of the formula [A] a [M] b [X] c Compounds of formula [Z] p O q In a specific exemplary embodiment, the stable crystalline A / M / X material of the present invention is substantially free of aliphatic ligands, preferably completely free of aliphatic ligands, wherein "aliphatic ligands" are as defined herein. "Substantially free of aliphatic ligands" means that the stable crystalline A / M / X material includes less than 0.5 wt%, preferably less than 0.01 wt%, and more preferably less than 0.001 wt% of aliphatic ligands.

[0387] Formula [A] a [M] b [X] c A compound of formula [Z] p O q In short, preferably, p is 1 to 3 and q is 1 to 8. The element Z is each selected from Al, Si, Zr, Ga, Ba, Nb, Mg, Y, Ni and Zn, preferably Al, Zr or Si, most preferably Al.

[0388] The A cations are each generally selected from alkali metal cations, C 1-10 Alkyl ammonium ion, C 2-10 Alkenyl ammonium ion, iminium ion, C 1-10 Alkyl iminium ion, C 3-10 Cycloalkylammonium ions and C 3-10 Cycloalkyliminium ion, wherein the above C 1-10 Alkyl ammonium ion, C 2-10 Alkenyl ammonium ion, iminium ion, C 1-10 Alkyl iminium ion, C 3-10 Cycloalkylammonium ions and C 3-10 The cycloalkyliminium ion is optionally selected from amino, C 1-6 Alkylamino, imino, C 1-6 Alkyl imine, C 1-6 Alkyl, C 2-6 Alkenyl, C 3-6Cycloalkyl and C 6-12 The aromatic group is substituted by one or more substituents; preferably selected from Cs + , Rb + , methylammonium ion, ethylammonium ion, propylammonium ion, butylammonium ion, pentylammonium ion, hexylammonium ion, heptylammonium ion, octylammonium ion, formamidinium ion, benzylammonium ion, phenethylammonium ion, benzylammonium ion, naphthylmethylammonium ion and one or more of guanimine ion.

[0389] Each M cation is generally selected from a metal or metalloid cation, preferably from Li + 、Na + , K + , Rb + , Cs + , Cu + 、Ag + 、Au + , Hg + , 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+ 、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+ One or more of, preferably selected from Cu + 、Ag + 、Au + Sn 2+ , Pb 2+ , Cu 2+ ,Ge 2+ 、Ni 2+ 、Bi 3+ and Sb 3+ ; Pb is particularly preferred 2+ .

[0390] The X anions are each generally selected from F - , Cl - Br - or I - , preferably Cl - or Br - .

[0391] Particularly preferably, formula [A] a [M] b [X] c The compound of formula [A] [M] [X] 3 is a compound of formula [A] [M] [X] 3. Such compounds are exemplified herein.

[0392] It is further particularly preferred that [A] comprises two or more A cations, preferably, [A] comprises Cs + and Rb + Compounds of this type have been shown to degrade particularly rapidly with previous stabilization methods, but have been shown to retain their photoluminescent properties for at least 300 hours with the oxide stabilization described herein.

[0393] The crystalline products of the present invention can be manipulated and modified for use in optoelectronic devices. For example, the stable crystalline A / M / X material can be ground into a coarse powder. For example, the powder can be used to coat a surface, or can be embedded in a carrier material such as a polymer. Coarse powder refers to a powder whose particles are not smaller than the crystal grains, so that the oxide coating on the crystal (if any) is generally intact.

[0394] Thus, the present invention provides a coarse particle size powder comprising a stable crystalline A / M / X material as defined herein.

[0395] In other embodiments, the stable crystalline A / M / X material of the present invention is formed into a thin film. Accordingly, the present invention provides a thin film comprising a stable crystalline A / M / X material as defined herein.

[0396] Photoactive Materials

[0397] The stable crystalline A / M / X materials of the present invention are generally semiconductors and are generally strong and stable emitters of visible light (i.e., light with a wavelength of about 450 nm to about 700 nm). Therefore, such stable crystalline A / M / X materials are very useful in a wide range of electronic devices. Exemplary optoelectronic devices and their manufacture are described in WO 2013 / 171517, WO 2013 / 171518, WO 2013 / 171520, WO 2014 / 045021, WO 2017 / 017441, WO 2017 / 037448, and WO 2017 / 089819, the entire contents of which are incorporated herein by reference.

[0398] For integration into optoelectronic devices, the stable crystalline A / M / X materials of the present invention are typically provided as photoactive materials. The photoactive material may consist entirely of the stable A / M / X materials defined herein, or may include other components. Thus, the present invention provides a photoactive material comprising the stable crystalline A / M / X materials of the present invention, for example a luminescent material comprising the stable crystalline A / M / X materials of the present invention.

[0399] As used herein, the term "photoactive material" refers to a material that can absorb and / or emit photons. Photoactive materials can achieve one or more of the following:

[0400] (i) Absorb photons which then generate free charge carriers such as electrons and holes; these materials are called light absorbing materials.

[0401] (ii) Absorb photons with energy higher than their band gap and re-emit photons at the energy of the band gap (these materials are called light-emitting materials); one type of light-emitting material is a luminescent material, which refers to a material that emits light after absorbing photons, i.e., a phosphorescent material or a fluorescent material.

[0402] (iii) accepting charges, including electrons and holes, which can subsequently recombine and emit light.

[0403] Photoactive materials are examples of semiconductor materials. As used herein, "semiconductor or semiconductor material" refers to a material with an electrical conductivity between a conductor and a dielectric. A semiconductor may have a band gap of 0.5 to 3.5 eV, such as a band gap of 0.5 to 2.5 eV or 1.0 to 2.0 eV (when measured at 300 K). Thus, the present invention provides a semiconductor material comprising a stable crystalline A / M / X material of the present invention.

[0404] The photoactive material of the present invention is generally capable of absorbing and / or emitting photons in the visible region of the spectrum, such as photons in the blue light region of the visible spectrum. Therefore, the photoactive material can be described as a light emitting material (i.e., a material that can emit light) or a light absorbing material (i.e., a material that can absorb light). For example, the photoactive material of the present invention can generally emit and / or absorb photons having at least one wavelength of 450 to 700 nm, such as 450 to 650 nm. In a preferred embodiment, the peak emission wavelength of the stable A / M / X material of the present invention is in the range of 450 to 500 nm, preferably in the range of 455 to 495 nm, and particularly preferably in the range of 460 to 490 nm. However, photoactive materials that can absorb and emit photons do not usually show an absorption onset and an emission peak at exactly the same wavelength.

[0405] The absorption onset value refers to the wavelength at which the photoactive material begins to significantly absorb photons from the perspective of moving from long wavelength to short wavelength, and the emission peak refers to the wavelength at which the photoactive material emits photons with the highest intensity. Typically, the emission peak of the photoactive material is 1000 nm or less, preferably 700 nm or less, such as 650 nm or less. In a preferred embodiment, the stable A / M / X material of the present invention has a peak emission wavelength in the range of 450 to 500 nm, preferably in the range of 455 to 495 nm, and particularly preferably in the range of 460 to 490 nm.

[0406] The photoactive material may include greater than or equal to 5 wt % of the stable crystalline A / M / X material of the present invention. Typically, at least 50 wt % of the photoactive material is composed of the stable crystalline A / M / X material defined herein. The photoactive material may include additional components discussed herein, such as a scaffold material, a matrix material, or a coating. But typically, the photoactive material includes greater than or equal to 80 wt % of the stable crystalline A / M / X material defined herein. Preferably, the photoactive material includes greater than or equal to 95 wt % of the stable crystalline A / M / X material, for example, greater than or equal to 99 wt % of the stable crystalline A / M / X material. The photoactive material may consist of or consist essentially of a stable crystalline A / M / X material.

[0407] The photoactive material is typically a solid.

[0408] The photoactive material may comprise a stable crystalline A / M / X material as defined herein. Thus, in one embodiment, the photoactive material comprises a coarse-grained powder of a stable crystalline A / M / X material. In another embodiment, the photoactive material may comprise a thin film of a stable crystalline A / M / X material. Typically, a stable crystalline A / M / X material is polycrystalline, and accordingly, the photoactive material comprises a polycrystalline stable crystalline A / M / X material of the present invention. In other embodiments, the photoactive material comprises nanocrystals of a stable crystalline A / M / X material.

[0409] The photoactive material may be in any form. Typically the photoactive material is in the form of a layer. A photoactive material in layer form is typically at least 1 nm thick. A layer of photoactive material may be up to 10 mm thick, for example where the layer is intended as a free-standing component of a device. Typically the layer of photoactive material is from 2 nm to 1 mm thick, more typically from 5 nm to 5 μm thick.

[0410] The layer of photoactive material may include a stable crystalline A / M / X material within the layer. The amount of the material within the layer may vary depending on the other components in the layer (such as any coating, matrix or scaffold material). In some embodiments, the photoactive material may be essentially composed of a layer of stable crystalline A / M / X material as defined herein. For example, the photoactive material may be entirely composed of a stable crystalline A / M / X material of the present invention. However, more generally, the photoactive material may include at least 50wt% of a stable crystalline A / M / X material, such as at least 70wt%, 80wt% or 80% of a stable crystalline A / M / X material. In some embodiments, the photoactive material may include at least 95wt% of a stable crystalline A / M / X material. Typically, a layer of photoactive material according to the present invention includes up to 99.9wt% of a stable crystalline A / M / X material.

[0411] The photoactive material may comprise multiple layers. Some or all of such layers may comprise stable crystalline A / M / X materials.

[0412] When the photoactive material is present in the form of a layer, the stable crystalline A / M / X material may be uniformly or non-uniformly distributed throughout the layer. For example, the photoactive material may include a layer consisting essentially of or consisting only of the stable crystalline A / M / X material. Alternatively or additionally, the photoactive material may include a substrate having the stable crystalline A / M / X material on the substrate (e.g., in the form of a coarse-grained powder or a thin film).

[0413] In some embodiments, the photoactive material may include one or more stable crystalline A / M / X materials of the present invention in the form of a thin film. The thin film typically includes a polycrystalline material disposed on a substrate.

[0414] In some embodiments, the photoactive materials of the present invention include a host material. That is, the photoactive materials of the present invention may include one or more stable A / M / X materials of the present invention and a host material.

[0415] In the case where the photoactive material of the present invention includes a matrix material, the photoactive material generally includes particles of one stable crystalline A / M / X material of the present invention suspended in one or more matrix materials. "Particles" refers to a coarse-grained powder or crystals (e.g., nanocrystals) of a stable crystalline A / M / X material. Preferably, in the case where the photoactive material includes a matrix material, the photoactive material includes nanocrystals of one or more stable crystalline A / M / X materials of the present invention suspended in the matrix material.

[0416] Suitable host materials are described in WO 2017 / 017441, the entire contents of which are incorporated herein by reference. Host materials are any suitable materials in which a plurality of nanoparticles can be suspended. Host materials are generally solid. Host materials are generally non-reactive, and they do not chemically react with the nanoparticles or any other part (such as a metal component) in the light-emitting device. Host materials generally have high transparency to most of the light in the visible spectrum.

[0417] The matrix material may be an inorganic material or an organic material. The matrix material is typically stable at temperatures up to 150° C. or up to 100° C. Typically, the matrix material comprises a polymer matrix material.

[0418] The polymer matrix material is a matrix material comprising a polymer. The polymer matrix material generally comprises the following polymers: polyolefins (e.g., polyethylene, polypropylene, polybutylene, polymethyl methacrylate or polystyrene), polyesters (e.g., polyethylene terephthalate, polyhydroxybutyrate or polyethylene adipate), polyurethanes, polycarbonates, polyimides, polyamides (e.g., polyamide 6 or polyamide 66) or epoxy resins. Preferably, the polymer matrix material comprises a polymer selected from polymethyl methacrylate, polystyrene, polyurethanes, polycarbonates, polyimides, polyamides or epoxy resins.

[0419] The inorganic matrix material is typically an inorganic oxide, such as a metal oxide. Examples of inorganic matrix materials include ZnO, NiO, and SnO2. Other examples of inorganic matrix materials include large bandgap perovskites, such as perovskites with a bandgap of 3 eV or more, preferably 4 eV or more. However, these large bandgap perovskites are less preferred matrix materials compared to inorganic oxides.

[0420] In some embodiments, the matrix material is a semiconductor material. Examples of suitable semiconductor matrix materials include polyvinylcarbazole, polyfluorene derivatives, and CBP (4,4′-bis(N-carbazolyl)-1,1′-biphenyl).

[0421] Thus, in some embodiments, the photoactive material comprises nanoparticles of one or more stable crystalline A / M / X materials of the present invention and a matrix material selected from the group consisting of polymethyl methacrylate, polystyrene, polyurethane, polycarbonate, polyimide, polyamide, epoxy resin, ZnO, NiO and SnO2, polyvinylcarbazole, polyfluorene derivatives and CBP (4,4′-bis(N-carbazolyl)-1,1′-biphenyl).

[0422] In the case where the photoactive material includes a host material, the photoactive material typically includes up to 50 wt% of the host material. For example, the photoactive material typically includes up to 40 wt%, up to 30 wt%, or up to 20 wt% of the host material. In these embodiments, the photoactive material typically includes at least 50 wt% of the stable crystalline A / M / X material of the present invention.

[0423] In the case where the photoactive material comprises a matrix material, the photoactive material is typically present in the form of a layer. The thickness of the layer is typically from 100 nm to 4 mm, for example from 1 μm to 1000 μm or from 50 μm to 500 μm. In some cases, the layer may have a thickness of 1 to 4 mm, for example if a free-standing layer is to be constructed.

[0424] In some embodiments, the photoactive material includes a scaffold material. The scaffold material is typically a solid material. The scaffold material is typically a solid support on which one or more stable crystalline A / M / X materials of the present invention are distributed.

[0425] In some embodiments, the photoactive material of the present invention comprises a porous scaffold and one or more stable crystalline A / M / X materials of the present invention. Typically, the porous scaffold material is in contact with the one or more stable crystalline A / M / X materials. Suitable examples of porous scaffold materials are described in WO 2013 / 171518, the entire contents of which are incorporated herein by reference.

[0426] Typically, the stable crystalline A / M / X material of the present invention is disposed on the surface of the scaffold material. Typically, where the scaffold is a porous scaffold, the stable crystalline A / M / X material is disposed on the surface of the porous scaffold material, so that it is supported on the surface of the pores within the scaffold. In these embodiments, the stable crystalline A / M / X material of the present invention is distributed on one or more inner surfaces of the scaffold material, so that it can be said that the material is distributed within the scaffold material. In this case, the stable crystalline A / M / X material is typically used as a light-absorbing photosensitive material and as a charge transport material. A photoactive material comprising a stable crystalline A / M / X material and a scaffold material (e.g., a porous scaffold material) can advantageously quickly transport charge carriers through the photoactive material.

[0427] The support material is generally a dielectric support material or an n-type support material. Preferably, the support material is a porous dielectric support material or a porous n-type support material.

[0428] "Dielectric material" refers to an insulating material. The dielectric support material may include a material having a band gap greater than or equal to 3.6 eV, or greater than or equal to 4 eV. The dielectric support material is typically a dielectric oxide. The dielectric support material typically includes one or more oxides of aluminum, germanium, zirconium, silicon, yttrium or ytterbium. However, the dielectric support material may include one or more of polymethyl methacrylate (PMMA), polystyrene, polycarbonate or polyimide. The dielectric support material may preferably be selected from aluminum silicate, zirconium oxide, aluminum oxide and silicon dioxide, for example aluminum oxide (Al2O3).

[0429] The n-type scaffold may be selected from any n-type material described herein, such as titanium dioxide (TiO2). "N-type material" refers to an electron transport material.

[0430] Suitable n-type materials are generally inorganic materials. Suitable n-type inorganic materials may be selected from metal oxides, metal sulfides, metal selenides, metal tellurides, perovskites, amorphous silicon, n-type IV semiconductors, n-type III-V semiconductors, n-type II-VI semiconductors, n-type I-VII semiconductors, n-type IV-VI semiconductors, n-type V-VI semiconductors, and n-type II-V semiconductors, any of which may be doped or undoped. More generally, n-type materials are selected from metal oxides, metal sulfides, metal selenides, and metal tellurides. The n-type material may include an inorganic material selected from an oxide of the following metals, or an oxide of a mixture of two or more of the metals: titanium, tin, zinc, niobium, tantalum, tungsten, indium, gallium, neodymium, palladium, or cadmium. For example, the n-type material may include TiO2, SnO2, ZnO, Nb2O5, Ta2O5, WO3, W2O5, In2O3, Ga2O3, Nd2O3, PbO or CdO. Other suitable n-type materials that can be used include sulfides of cadmium, tin, copper or zinc, including sulfides of mixtures of two or more of the metals. For example, the sulfide may be FeS2, CdS, ZnS or Cu2ZnSnS4. The n-type material may, for example, include selenides of cadmium, zinc, indium or gallium or selenides of mixtures of two or more of the metals; or tellurides of cadmium, zinc, cadmium or tin or tellurides of mixtures of two or more of the metals. For example, the selenide may be Cu(In,Ga)Se2. Typically, the telluride is a telluride of cadmium, zinc, cadmium or tin. For example, the telluride may be CdTe. The n-type material may include, for example, an inorganic material selected from the following: an oxide of titanium, tin, zinc, niobium, tantalum, tungsten, indium, gallium, neodymium, palladium, cadmium, or a mixture of two or more of the metals; a sulfide of cadmium, tin, copper, zinc, or a mixture of two or more of the metals; a selenide of cadmium, zinc, indium, gallium, or a selenide of a mixture of two or more of the metals; or a telluride of cadmium, zinc, cadmium or tin, or a telluride of a mixture of two or more of the metals. Examples of other semiconductors that are suitable n-type materials, for example if they are n-doped, include Group IV compound semiconductors; amorphous silicon; Group III-V semiconductors (e.g., gallium arsenide); Group II-VI semiconductors (e.g., cadmium selenide); Group I-VII semiconductors (e.g., cuprous chloride); Group IV-VI semiconductors (e.g., lead selenide); Group V-VI semiconductors (e.g., bismuth telluride) and Group II-V semiconductors (e.g., cadmium arsenide). Typically, the n-type material includes TiO2.

[0431] Therefore, in some embodiments, the photoactive material of the present invention may include the stable crystalline A / M / X material of the present invention and a porous support material, preferably, the dielectric support material is selected from one or more of alumina, silica and titania.

[0432] In the case where the photoactive material includes a scaffold material, the photoactive material is generally present in the form of a layer. Typically, the thickness of the layer is from 10 nm to 5000 nm, for example, the thickness may be from 400 nm to 800 nm. Typically, the thickness of the layer is from 100 nm to 700 nm.

[0433] The layer of photoactive material of the present invention may be free of open porosity. The layer of photoactive material may comprise a layer of stable crystalline A / M / X material of the present invention, wherein the layer of stable crystalline A / M / X material is free of open porosity. Alternatively, the layer of photoactive material may be porous, or the layer of photoactive material may be deposited on a porous support as described herein.

[0434] Optoelectronic devices

[0435] The invention further provides an optoelectronic device comprising a photoactive material as defined herein. Accordingly, the invention provides an optoelectronic device comprising a stable crystalline A / M / X material as defined herein, a coarse grained powder as defined herein or a thin film as defined herein.

[0436] As used herein, the term "optoelectronic device" refers to a device that emits, controls, detects or emits light. Typically, the light is visible light, such as light having a wavelength of about 450 to 700 nm. In a preferred embodiment, the device is capable of emitting blue light (i.e., light having a wavelength of about 450 to 500 nm, preferably about 455 to 495 nm, and more preferably about 460 to 490 nm). The optoelectronic device of the present invention includes the photoactive material of the present invention, and thus can achieve one or more of the following:

[0437] (i) Absorption of photons, which then generate free charge carriers such as electrons and holes;

[0438] (ii) absorb photons with energies above its band gap and re-emit photons at the energy of the band gap; and

[0439] (iii) accepting charges, including electrons and holes, which can subsequently recombine and emit light.

[0440] In a preferred embodiment, the present invention provides an optoelectronic device, which is a photovoltaic device, comprising a photoactive material as defined herein. A "photovoltaic device" herein refers to a device capable of converting electrical energy into light, particularly visible light. In a preferred embodiment, the photovoltaic device is capable of converting electrical energy into blue light (i.e. light having a wavelength of about 450 to 500 nm, preferably about 455 to 495 nm, more preferably about 460 to 490 nm).

[0441] In another preferred embodiment, the present invention provides an optoelectronic device that is capable of generating photons outside the visible spectrum, particularly in the infrared region, such as 700 to 1500 nm. Therefore, in a preferred embodiment, the present invention provides an optoelectronic device that is a light emitting diode that is capable of converting electrical energy into photons with a wavelength of 700 to 1500 nm. Such optoelectronic devices are most useful because there is a widespread demand for infrared emitters, particularly in the field of communications technology. Many A / M / X materials can emit light in the IR region of the spectrum and can be used to make such optoelectronic devices. For example, Sn-based [A]Pb y Sn 1-x [X]3 family of compounds that emit light with a wavelength of 700 to 1000 nm. Since Sn is required to maintain charge neutrality in the crystal 2+ Ion oxidation to Sn 4+ , these particular materials are usually affected by instability. Therefore, the stability imparted by the method of the present invention is most advantageous in stabilizing these compounds and in producing photoactive materials including these substances for various optoelectronic devices, including LED and photovoltaic applications.

[0442] In another preferred embodiment, the present invention provides an optoelectronic device, which is a light emitting device, comprising a photoactive material as defined herein. The light emitting device may be a light emitting diode (LED). The light emitting device of the present invention is generally capable of emitting visible light. In a preferred embodiment, the light emitting device is capable of emitting blue light (i.e., light having a wavelength of about 450 to 500 nm, preferably about 455 to 495 nm, more preferably about 460 to 490 nm).

[0443] In some preferred embodiments, the optoelectronic device of the present invention includes a photoactive material, wherein the photoactive material is disposed in a layer. A layer of photoactive material is defined herein; typically, the layer of photoactive material has a thickness of at least 2 nm. However, in some embodiments, when the layer is intended to exist in a free-standing form, the layer can be very thick (e.g., up to 10 mm thick, more typically up to 5 mm thick).

[0444] In some embodiments, optoelectronic devices of the present invention include a layer of photoactive material that is a thin photosensitive layer, for example, having a thickness of 5 nm to 50 nm.

[0445] In a device where the layer of photoactive material forms a planar heterojunction with an n-type region or a p-type region, the layer of photoactive material may have a thickness greater than or equal to 100 nm. Preferably, the layer of photoactive material has a thickness of 100 nm to 700 nm, such as 200 nm to 500 nm. As used herein, the term "planar heterojunction" means that the surface defining the junction between the semiconductor material and the n-type or p-type region is substantially planar and has a low roughness, such as a root mean square roughness of less than 20 nm over an area of ​​25 nm x 25 nm, such as a root mean square roughness of less than 10 nm over an area of ​​25 nm x 25 nm, or less than 5 nm.

[0446] Photoactive materials are often used as photoactive components (eg, light absorbing components or light emitting components) within optoelectronic devices. In other embodiments, the semiconductor material may form a layer of a p-type or n-type semiconductor in an optoelectronic device (eg, a solar cell or LED).

[0447] Typically, the optoelectronic device of the present invention is a photovoltaic device, wherein the photovoltaic device comprises:

[0448] (a) an n-type region including at least one n-type layer;

[0449] (b) a p-type region including at least one p-type layer; and disposed between the n-type region and the p-type region:

[0450] (c) Layer of photoactive material.

[0451] Preferred examples of the optoelectronic device of the present invention include LEDs, photodiodes, solar cells, photodetectors or light sensors; LEDs, photodiodes or solar cells are particularly preferred.

[0452] For example, the optoelectronic device may include:

[0453] an n-type region including at least one n-type layer;

[0454] A p-type region including at least one p-type layer; and disposed between the n-type region and the p-type region:

[0455] The layer of photoactive material comprises (or consists essentially of) a stable crystalline A / M / X material of the present invention.

[0456] The n-type region comprises at least one n-type layer. The n-type region typically comprises one or two n-type layers. Each layer may be porous or dense. A dense layer typically refers to a layer without open porosity (e.g., without any mesoporous or macroporous porosity). The p-type region comprises at least one p-type layer. The p-type region typically comprises one or two p-type layers. Each layer may be porous or dense. A dense layer typically refers to a layer without open porosity. It may be a non-porous layer.

[0457] In some cases, the optoelectronic device comprises a layer of the photoactive material without open porosity. The layer of the photoactive material without open porosity is typically a crystalline layer of a stable crystalline A / M / X material (preferably a perovskite) according to the present invention without open porosity. Thus, the layer of photoactive material may comprise greater than or equal to 95 vol% of one or more stable crystalline A / M / X materials of the present invention (thus less than 5 vol% non-porous volume). The layer without open porosity typically does not include macropores or mesopores.

[0458] The layer of photoactive material typically forms a planar heterojunction with either the n-type region or the p-type region. The layer of photoactive material typically forms a first planar heterojunction with the n-type region and a second planar heterojunction with the p-type region. This forms a planar heterojunction device of the kind described in WO 2014 / 045021. The term "planar heterojunction" as used herein refers to a junction between two regions where one region does not penetrate into the other region. This does not require that the junction is completely smooth, only that one region does not substantially penetrate into the pores of the other region.

[0459] When the layer of photoactive material forms a planar heterojunction with both the p-type and n-type regions, a thin film device is typically formed. The thickness of the layer of photoactive material may be greater than or equal to 50 nm.

[0460] In some embodiments, it is preferred that a porous support material is present, wherein the porous support is as defined herein. The support material can help transfer charges from the photoactive material to adjacent areas. The support material can also or alternatively help form a layer of photoactive material during device construction. Thus, in some embodiments, an optoelectronic device comprises:

[0461] an n-type region including at least one n-type layer;

[0462] a p-type region including at least one p-type layer; and a layer of a photoactive material disposed between the n-type region and the p-type region and including:

[0463] (i) a porous scaffold material; and

[0464] (ii) Stable crystalline A / M / X material in contact with the scaffold material.

[0465] The architecture of such devices is described in more detail in WO 2014 / 045021, the entire contents of which are incorporated herein by reference.

[0466] The layer of photoactive material comprising the porous scaffold material and the stable crystalline A / M / X material may form a sensitizing layer of the photoactive material. Thus, the optoelectronic device may be a sensitizing device.

[0467] Further details about the architecture of optoelectronic devices such as solar cells and suitable materials thereof are described in published application WO 2017 / 037448, the entire contents of which are incorporated herein by reference. The stable crystalline A / M / X materials of the present invention can be used to replace the semiconductor materials therein.

[0468] In some embodiments, an optoelectronic device comprises:

[0469] an n-type region including at least one n-type layer;

[0470] A p-type region including at least one p-type layer; and disposed between the n-type region and the p-type region:

[0471] (i) a first layer comprising a porous scaffold material and the stable crystalline A / M / X material; and

[0472] (ii) a capping layer disposed on the first layer, the capping layer being a layer of the stable crystalline A / M / X material without open porosity,

[0473] Wherein, the stable crystalline A / M / X material in the capping layer is in contact with the stable crystalline A / M / X material in the first layer.

[0474] The first layer includes the porous scaffold material and the stable crystalline A / M / X material disposed on the surface of the scaffold material. The term "scaffold material" as used herein refers to a material whose function includes serving as a physical support for another material. In the current example, the scaffold material serves as a support for the stable crystalline A / M / X material present in the first layer. The stable crystalline A / M / X material is disposed on or supported on the surface of the scaffold material. The porous scaffold material generally has an open porous structure. Therefore, the "surface" of the porous scaffold material here generally refers to the surface of the pores within the scaffold material. Therefore, the stable crystalline A / M / X material in the first layer is generally disposed on the surface of the pores within the scaffold material.

[0475] In some embodiments, the scaffold material is porous and the stable crystalline A / M / X material in the first layer is disposed in the pores of the scaffold material. The effective porosity of the scaffold material is typically at least 50%. For example, the effective porosity may be about 70%. In one embodiment, the effective porosity is at least 60%, such as at least 70%.

[0476] Typically, the stable crystalline A / M / X material (or photoactive material) in the first layer contacts one of the p-type region and the n-type region, and the stable crystalline A / M / X material in the capping layer contacts the other of the p-type region and the n-type region. The stable crystalline A / M / X material in the capping layer typically forms a planar heterojunction with the p-type region or the n-type region.

[0477] In one embodiment, the stable crystalline A / M / X material in the capping layer contacts the p-type region, and the stable crystalline A / M / X material in the first layer contacts the n-type region. In another embodiment, the stable crystalline A / M / X material in the capping layer contacts the n-type region, and the stable crystalline A / M / X material in the first layer contacts the p-type region (e.g., in an inverted device).

[0478] In one embodiment, the stable crystalline A / M / X material in the capping layer contacts the p-type region, and the stable crystalline A / M / X material in the first layer contacts the n-type region. Typically, in this embodiment, the scaffold material is an electron transport scaffold material or a dielectric scaffold material. Typically, the stable crystalline A / M / X material in the capping layer forms a planar heterojunction with the p-type region.

[0479] However, in another embodiment, the stable crystalline A / M / X material in the capping layer contacts the n-type region, and the stable crystalline A / M / X material in the first layer contacts the p-type region. Typically, in this embodiment, the scaffold material is a hole transport scaffold material or a dielectric scaffold material. Typically, the stable crystalline A / M / X material in the capping layer forms a planar heterojunction with the n-type region.

[0480] The thickness of the capping layer is typically greater than the thickness of the first layer. Therefore, most of the photoactivity (e.g., light absorption or light emission) typically occurs in the capping layer. The thickness of the capping layer is typically 10 nm to 100 μm. More typically, the thickness of the capping layer is 10 nm to 10 μm. Preferably, the thickness of the capping layer is 50 nm to 1000 nm, or, for example, 100 nm to 700 nm. The thickness of the capping layer may be greater than or equal to 100 nm. On the other hand, the thickness of the first layer is typically 5 nm to 1000 nm. More typically, it is from 5 nm to 500 nm, or, for example, from 30 nm to 200 nm.

[0481] The n-type region is typically an n-type layer. Alternatively, the n-type region may include an n-type layer and an n-type exciton blocking layer. Such an n-type exciton blocking layer is typically disposed between the n-type layer and the layer comprising a stable crystalline A / M / X material. The n-type region may have a thickness from 50 nm to 1000 nm. For example, the n-type region may have a thickness from 50 nm to 500 nm, or from 100 nm to 500 nm.

[0482] Preferably, the n-type region comprises a dense layer of n-type semiconductor. The n-type region may further comprise a porous layer of n-type semiconductor, which may be a porous support material as described above (wherein the porous support material is an electron transport material).

[0483] The n-type region in the optoelectronic device of the present invention includes one or more n-type layers. Typically, the n-type region is an n-type layer, i.e., a single n-type layer. However, in other embodiments, the n-type region may include an n-type layer and an n-type exciton blocking layer. In the case of an n-type exciton blocking layer, the n-type exciton blocking layer is typically disposed between the n-type layer and the layer comprising a stable crystalline A / M / X material.

[0484] An exciton blocking layer is a material that has a wider band gap than the stable crystalline A / M / X material, but has a conduction band or valence band that closely matches the conduction band or valence band of the stable crystalline A / M / X material. If the conduction band (or lowest unoccupied molecular orbital energy level) of the exciton blocking layer closely matches the conduction band of the stable crystalline A / M / X, then electrons can enter and pass through the exciton blocking layer from the stable crystalline A / M / X material, or pass through the exciton blocking layer and enter the stable crystalline A / M / X material, which we call an n-type exciton blocking layer. One such example is bathocuproin, described in P. Peumans, A. Yakimov and SR Forrest, "Small molecular weight organic thin-film photodetectors and solar cells" J. Appl. Phys. 93, 3693 (2001) and Masaya Hirade and Chihaya Adachi, "Smallmolecular organic photovoltaic cells with exciton blocking layer at anode interface for improved device performance" Appl. Phys. Lett. 99, 153302 (2011)}.

[0485] The n-type layer refers to a layer of electron transport (ie, n-type) material. For example, the n-type material may be a single n-type compound or single substance material, which may be undoped or doped with one or more doping elements.

[0486] The n-type layer employed in the photovoltaic devices of the present invention may comprise inorganic or organic n-type materials.

[0487] Suitable inorganic n-type materials may be selected from metal oxides, metal sulfides, metal selenides, metal tellurides, perovskites, amorphous Si, n-type Group IV semiconductors, n-type Group III-V semiconductors, n-type Group II-VI semiconductors, n-type Group I-VII semiconductors, n-type Group IV-VI semiconductors, n-type Group V-VI semiconductors and n-type Group II-V semiconductors, any of which may be doped or undoped.

[0488] The n-type material may be selected from metal oxides, metal sulfides, metal selenides, metal tellurides, amorphous Si, n-type Group IV semiconductors, n-type Group III-V semiconductors, n-type Group II-VI semiconductors, n-type Group I-VII semiconductors, n-type Group IV-VI semiconductors, n-type Group V-VI semiconductors and n-type Group II-V semiconductors, any of which may be doped or undoped.

[0489] More typically, the n-type material is selected from metal oxides, metal sulfides, metal selenides, and metal tellurides.

[0490] The n-type layer may include an inorganic material selected from the group consisting of an oxide of a metal, or an oxide of a mixture of two or more of the metals: titanium, tin, zinc, niobium, tantalum, tungsten, indium, gallium, neodymium, palladium, or cadmium. For example, the n-type layer may include TiO2, SnO2, ZnO, Nb2O5, Ta2O5, WO3, W2O5, In2O3, Ga2O3, Nd2O3, PbO, or CdO.

[0491] Other suitable n-type materials that may be used include sulfides of cadmium, tin, copper or zinc, including sulfides of mixtures of two or more of the metals. For example, the sulfide may be FeS2, CdS, ZnS, SnS, BiS, SbS or Cu2ZnSnS4.

[0492] The n-type layer may include, for example, a selenide of cadmium, zinc, indium or gallium, or a selenide of a mixture of two or more of the metals; or a telluride of cadmium, zinc, cadmium or tin, or a telluride of a mixture of two or more of the metals. For example, the selenide may be Cu(In,Ga)Se2. Typically, the telluride is a telluride of cadmium, zinc, cadmium or tin. For example, the telluride may be CdTe.

[0493] The n-type layer may include, for example, an inorganic material selected from the group consisting of: oxides of titanium, tin, zinc, niobium, tantalum, tungsten, indium, gallium, neodymium, palladium, cadmium, or oxides of a mixture of two or more of the metals; sulfides of cadmium, tin, copper, zinc, or a mixture of two or more of the metals; selenides of cadmium, zinc, indium, gallium, or a mixture of two or more of the metals; or tellurides of cadmium, zinc, cadmium, or tin, or a mixture of two or more of the metals. Examples of other semiconductors that are suitable n-type materials, for example if they are n-doped, include group IV elemental or compound semiconductors; amorphous silicon; group III-V semiconductors (e.g., gallium arsenide); group II-VI semiconductors (e.g., cadmium selenide); group I-VII semiconductors (e.g., cuprous chloride); group IV-VI semiconductors (e.g., lead selenide); group V-VI semiconductors (e.g., bismuth telluride) and group II-V semiconductors (e.g., cadmium arsenide).

[0494] Typically, the n-type layer comprises TiO2.

[0495] When the n-type layer is an inorganic material, such as TiO2 or any of the other materials listed above, it can be a dense layer of the inorganic material. Preferably, the n-type layer is a dense layer of TiO2.

[0496] Other n-type materials may also be used, including organic and polymer electron transport materials and electrolytes. Suitable examples include, but are not limited to, fullerenes or fullerene derivatives (e.g., C 60 or phenyl-C 61- butyric acid methyl ester (PCBM)); an organic electron transport material including perylene or its derivatives, or poly {[N,N0-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alternate-5,50-(2,20-bithiophene)} (P(NDI2OD-T2)).

[0497] The p-type region is typically a p-type layer. Alternatively, the p-type region may include a p-type layer and a p-type exciton blocking layer. Such a p-type exciton blocking layer is typically disposed between the p-type layer and a layer comprising a stable crystalline A / M / X material. The p-type region may have a thickness from 50 nm to 1000 nm. For example, the p-type region may have a thickness from 50 nm to 500 nm, or from 100 nm to 500 nm.

[0498] The p-type region in the optoelectronic device of the present invention includes one or more p-type layers. Typically, the p-type region is a p-type layer, i.e., a single p-type layer. However, in other embodiments, the p-type region may include a p-type layer and a p-type exciton blocking layer. In the case of a p-type exciton blocking layer, the p-type exciton blocking layer is typically disposed between the p-type layer and a layer comprising a stable crystalline A / M / X material. If the valence band (or highest occupied molecular orbital energy level) of the exciton blocking layer is closely aligned with the valence band of the stable crystalline A / M / X material, holes can enter and pass through the exciton blocking layer from the stable crystalline A / M / X material, or pass through the exciton blocking layer and enter the stable crystalline A / M / X material, which we call a p-type exciton blocking layer. Such an example is tris[4-(5-phenylthiophen-2-yl)phenyl]amine, described in Masaya Hirade and Chihaya Adachi, “Small molecular organic photovoltaic cells with exciton blocking layer at anode interface for improved device performance” Appl. Phys. Lett. 99, 153302 (2011).

[0499] The p-type layer refers to a layer of hole transport (i.e., p-type) material. The p-type material can be a single p-type compound or single substance material, or a mixture of two or more p-type compounds or single substances, which can be undoped or doped with one or more doping elements.

[0500] The p-type layer employed in the optoelectronic device of the present invention may comprise an inorganic or organic p-type material. Typically, the p-type region comprises a layer of an organic p-type material.

[0501] Suitable p-type materials can be selected from polymers or molecular hole transporters. For example, the p-type layer used in the optoelectronic device of the present invention may include spiro-OMeTAD (2,2',7,7'-tetra-(N,N-di-p-methoxyaniline) 9,9'-spirobifluorene), P3HT (poly (3-hexylthiophene)), PCPDTBT (poly [2,1,3-benzothiadiazole-4,7-diyl [4,4-bis (2-ethylhexyl) -4H-cyclopenta [2,1-b: 3,4-b'] dithiophene-2,6-diyl]]), PVK (poly (N-vinyl carbazole)), HTM-TFSI (1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide) Li-TFSI (bis (trifluoromethylsulfonyl) imide lithium) or tBP (tert-butylpyridine). The p-type region may include carbon nanotubes. Typically, the p-type material is selected from spiro-OMeTAD, P3HT, PCPDTBT and PVK. Preferably, the p-type layer used in the optoelectronic device of the present invention comprises spiro-OMeTAD.

[0502] The p-type layer may include, for example, spiro-OMeTAD (2,2',7,7'-tetrakis-(N,N-di-p-methoxyaniline)-9,9'-spirobifluorene), P3HT (poly(3-hexylthiophene)), PCPDTBT (poly[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b']dithiophene-2,6-diyl]]), or PVK (poly(N-vinylcarbazole)).

[0503] Suitable p-type materials also include molecular hole transporters, polymer hole transporters and copolymer hole transporters. The p-type material can be, for example, a molecular hole transport material, including a polymer or copolymer of one or more of the following parts: thienyl, phenylene, dithiazolyl, benzothiazolyl, diketopyrrolopyrrole, ethoxydithiophenyl, amino, triphenylamino, carbazolyl, ethylenedioxythienyl, dioxythienyl or fluorene. Therefore, the p-type layer used in the optoelectronic device of the present invention can, for example, include any of the above-mentioned molecular hole transport materials, polymers or copolymers.

[0504] Suitable p-type materials also include m-MTDATA (4,4′,4″-tris(methylphenylphenylamino)triphenylamine), MeOTPD (N,N,N′,N′-tetrakis(4-methoxyphenyl)-p-diaminobiphenyl), BP2T (5,5′-di(biphenyl-4-yl)-2,2′-bithiophene), Di-NPB (N,N′-di-[(1-naphthyl)-N,N′-diphenyl]-1,1′-biphenyl)-4,4′-diamine), α-NPB (N,N′-di(naphthyl-1-yl)-N,N′-biphenyl -p-diaminobenzidine), TNATA (4,4',4"-tris-(N-(naphthalen-2-yl)-N-anilino)triphenylamine), BPAPF (9,9-bis[4-(N,N-bis-biphenyl-4-yl-amino)phenyl]-9H-fluorene), spiro-NPB (N2,N7-di-1-naphthyl-N2,N7-diphenyl-9,9'-spirobis[9H-fluorene]-2,7-diamine), 4P-TPD (4,4-bis-(N,N-diphenylamino)-tetraphenyl), PEDOT:PSS, and spiro-OMeTAD.

[0505] For example, the p-type layer can be doped with tert-butylpyridine and LiTFSI. The p-type layer can be doped to increase the hole density. For example, the p-type layer can be doped with NOBF4 (nitrosonium tetrafluoroborate) to increase the hole density.

[0506] In other embodiments, the p-type layer may include an inorganic hole transporter. For example, the p-type layer may include an inorganic hole transporter containing: an oxide of nickel, vanadium, copper, or molybdenum; CuI, CuBr, CuSCN, Cu2O, CuO, or CIS; perovskite; amorphous Si; p-type IV semiconductor, p-type III-V semiconductor, p-type II-VI semiconductor, p-type I-VII semiconductor, p-type IV-VI semiconductor, p-type V-VI semiconductor, and p-type II-V semiconductor, wherein the inorganic material is doped or undoped. The p-type layer may be a dense layer of the inorganic hole transporter.

[0507] For example, the p-type layer may include an inorganic hole transporter containing: an oxide of nickel, vanadium, copper or molybdenum; CuI, CuBr, CuSCN, Cu2O, CuO or CIS; amorphous Si; a p-type IV semiconductor, a p-type III-V semiconductor, a p-type II-VI semiconductor, a p-type I-VII semiconductor, a p-type IV-VI semiconductor, a p-type V-VI semiconductor and a p-type II-V semiconductor, wherein the inorganic material is doped or undoped. The p-type layer may, for example, include an inorganic hole transporter selected from CuI, CuBr, CuSCN, Cu2O, CuO and CIS. The p-type layer may be a dense layer of the inorganic hole transporter.

[0508] Typically, the p-type layer comprises a polymer or molecular hole transporter, and the n-type layer comprises an inorganic n-type material. The p-type polymer or molecular hole transporter can be any suitable polymer or molecular hole transporter, such as any of those listed above. Likewise, the inorganic n-type material can be any suitable n-type inorganic, such as any of those listed above. For example, in one embodiment, the p-type layer comprises spiro-OMeTAD, and the n-type layer comprises TiO2. Typically, in this embodiment, the n-type layer comprising TiO2 is a dense layer of TiO2.

[0509] In other embodiments, both the n-type layer and the p-type layer include inorganic materials. Thus, the n-type layer may include an inorganic n-type material, and the p-type layer may include an inorganic p-type material. The inorganic p-type material may be any suitable p-type inorganic, such as any of those listed above. Likewise, the inorganic n-type material may be any suitable n-type inorganic, such as any of those listed above.

[0510] In other embodiments, the p-type layer comprises an inorganic p-type material (i.e., an inorganic hole transporter), and the n-type layer comprises a polymer or a molecular hole transporter. The inorganic p-type material can be any suitable p-type inorganic, such as any of those listed above. Similarly, the n-type polymer or molecular hole transporter can be any suitable n-type polymer or molecular hole transporter, such as any of those listed above.

[0511] For example, the p-type layer may include an inorganic hole transporter, and the n-type layer may include an electron transport material, wherein the electron transport material includes fullerene or a fullerene derivative, an electrolyte, or an organic electron transport material, preferably, the organic electron transport material includes perylene or a derivative thereof, or poly{[N,N0-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alternating-5,50-(2,20-dithiophene)}(P(NDI2OD-T2)). The inorganic hole transporter may include, for example, an oxide of nickel, vanadium, copper or molybdenum; CuI, CuBr, CuSCN, Cu2O, CuO or CIS; perovskite; amorphous Si; p-type IV semiconductor, p-type III-V semiconductor, p-type II-VI semiconductor, p-type I-VII semiconductor, p-type IV-VI semiconductor, p-type V-VI semiconductor and p-type II-V semiconductor, wherein the inorganic material is doped or undoped. More generally, the inorganic hole transporter includes an oxide of nickel, vanadium, copper or molybdenum; CuI, CuBr, CuSCN, Cu2O, CuO or CIS; p-type IV semiconductor, p-type III-V semiconductor, p-type II-VI semiconductor, p-type I-VII semiconductor, p-type IV-VI semiconductor, p-type V-VI semiconductor and p-type II-V semiconductor, wherein the inorganic material is doped or undoped. Thus, the inorganic hole transporter may include: oxides of nickel, vanadium, copper or molybdenum; CuI, CuBr, CuSCN, Cu2O, CuO or CIS.

[0512] The optoelectronic device generally further comprises one or more first electrodes and one or more second electrodes. The one or more first electrodes generally contact the n-type region, if such a region exists. The one or more second electrodes generally contact the p-type region, if such a region exists. Generally: the one or more first electrodes contact the n-type region and the one or more second electrodes contact the p-type region; or the one or more first electrodes contact the p-type region and the one or more second electrodes contact the n-type region.

[0513] The first and second electrodes may include any suitable conductive material. The first electrode typically includes a transparent conductive oxide. The second electrode typically includes one or more metals. Typically, the first electrode typically includes a transparent conductive oxide and the second electrode typically includes one or more metals.

[0514] The transparent conductive oxide may be as defined above and is typically FTO, ITO or AZO, and is typically ITO. The metal may be any metal. Typically the second electrode comprises a metal selected from silver, gold, copper, aluminum, platinum, palladium or tungsten. The electrode may form a single layer or may be patterned.

[0515] The optoelectronic device according to the present invention, such as a sensitized solar cell, may comprise the following layers in the following order:

[0516] I. one or more first electrodes as defined herein;

[0517] II. optionally a dense n-type layer as defined herein;

[0518] III. A porous layer of n-type material as defined herein;

[0519] IV. A layer of said stable crystalline A / M / X material (eg as a sensitizer).

[0520] V. a p-type region as defined herein;

[0521] VI. optionally a further densified p-type layer as defined herein; and

[0522] VII. One or more second electrodes as defined herein.

[0523] The optoelectronic device according to the present invention as a photovoltaic device may comprise the following layers in the following order:

[0524] I. one or more first electrodes as defined herein;

[0525] II. an n-type region as defined herein comprising at least one n-type layer;

[0526] III. A layer of photovoltaic material comprising a stable crystalline A / M / X material as defined herein;

[0527] IV. a p-type region as defined herein comprising at least one p-type layer; and

[0528] V. One or more second electrodes as defined herein.

[0529] The photovoltaic device according to the invention may comprise the following layers in the following order:

[0530] I. One or more first electrodes comprising a transparent conductive oxide, preferably FTO;

[0531] II. an n-type region as defined herein comprising at least one n-type layer;

[0532] III. A layer of a stable crystalline A / M / X material as defined herein;

[0533] IV. a p-type region as defined herein comprising at least one p-type layer; and

[0534] V. One or more second electrodes comprising a metal, preferably silver or gold.

[0535] A photovoltaic device (eg an inverted device) according to the present invention may comprise the following layers in the following order:

[0536] I. One or more second electrodes as defined herein.

[0537] II. an n-type region as defined herein comprising at least one n-type layer;

[0538] III. A layer of a stable crystalline A / M / X material as defined herein;

[0539] IV. a p-type region as defined herein comprising at least one p-type layer; and

[0540] V. One or more first electrodes as defined herein.

[0541] A photovoltaic device according to the present invention, such as a sensitized solar cell, may comprise the following layers in the following order:

[0542] I. one or more second electrodes comprising a metal;

[0543] II. an n-type region as defined herein comprising at least one mesoporous n-type layer;

[0544] III. A sensitizing layer of a stable crystalline A / M / X material as defined herein;

[0545] IV. a p-type region as defined herein comprising at least one p-type layer; and

[0546] V. one or more first electrodes comprising a transparent conductive oxide;

[0547] The one or more first electrodes may have a thickness of 100 nm to 700 nm, for example 100 nm to 400 nm. The one or more second electrodes may have a thickness of 10 nm to 500 nm, for example 50 nm to 200 nm or 10 nm to 50 nm. The n-type region may have a thickness of 50 nm to 500 nm. The p-type region may have a thickness of 50 nm to 500 nm.

[0548] Many of the above-described optoelectronic devices include a layer of a stable crystalline A / M / X material disposed on a previous layer in the device (e.g., a layer of semiconductor material, a layer of n-type semiconductor, a layer of p-type semiconductor, a support material, etc.). In these cases, the layer of stable crystalline A / M / X material in the device may be as described herein, for example, see page 23. The optoelectronic device may further include a subsequent layer disposed on the layer of stable crystalline A / M / X material. The subsequent layer disposed on the layer of stable crystalline A / M / X material may be prepared as described in WO 2017 / 037448.

[0549] In other embodiments, the photoactive material is used as a phosphor in an optoelectronic device. In these embodiments, the optoelectronic device generally comprises a light source and a photoactive material as defined herein. Generally, the photoactive material comprises a stable crystalline A / M / X material of the present invention in the form of a coarse-grained powder or in the form of nanocrystals. In addition, generally, the photoactive material comprises a matrix material as defined herein.

[0550] By "acting as a phosphor" it is meant that the function of the photoactive material is to absorb light at a first wavelength and subsequently re-emit light at a different, longer wavelength.

[0551] The light source is typically a white light source, a blue light source or a UV light source. That is, the light source is typically a source of electromagnetic radiation emitting at a wavelength below 500 nm, more typically below 480 nm. For example, the light source typically emits electromagnetic radiation at a wavelength of 400 to 480 nm.

[0552] Examples of optoelectronic devices in which the photoactive material is used as a phosphor include display screens, such as LED display screens, and solid state lighting devices.Such devices represent a further aspect of the present invention.

[0553] use

[0554] In another aspect, the present invention provides the use of the stable crystalline A / M / X material of the present invention and the photoactive material of the present invention comprising said compound.

[0555] In a first embodiment, the present invention provides the use of a stable crystalline A / M / X material or a photoactive material as defined herein as a light emitter, preferably a light emitter that emits light, preferably visible light (i.e. light in the wavelength range of 450 to 700 nm). In a preferred embodiment, the light emitter is capable of emitting blue light, i.e. light in the wavelength range of 450 to 500 nm, preferably 455 to 495 nm, more preferably 460 to 490 nm.

[0556] In a second embodiment, the present invention provides the use of a stable crystalline A / M / X material or a photoactive material as defined herein in the manufacture of an optoelectronic device, preferably, the optoelectronic device emits light, preferably visible light, and more preferably, the optoelectronic device emits blue light in the wavelength range of 450 to 500 nm, more preferably 455 to 495 nm, more preferably 460 to 490 nm.

[0557] In a third embodiment, the present invention provides the use of a stable crystalline A / M / X material or a photoactive material as defined herein as a phosphor. For example, the present invention provides the use of a photoactive material as defined herein in the manufacture of a screen, in particular an LED screen, or a solid-state lighting device.

[0558] In a fourth embodiment, the present invention further provides the use of a stable crystalline A / M / X material or an optoelectronic device as defined herein in a method for generating light (preferably visible light), more preferably in a method for generating light having a wavelength in the range of 450 to 500 nm, more preferably 455 to 495 nm, and further preferably 460 to 490 nm. For example, the present invention provides a method for generating light, the method comprising irradiating a stable crystalline A / M / X material or a photoactive material as defined herein with a light source; thereby generating emitted light having a wavelength in the range of 450 to 500 nm, more preferably 455 to 495 nm, and further preferably 460 to 490 nm from the photoactive material.

[0559] Example

[0560] 1. Materials

[0561] CsBr(99.9%), CsCl(99.9%), PbBr2(≥98%), PbCl2(≥98%), PbI2(≥98%),

[0562] HBr acid (48 wt % in water), N,N-dimethylformamide (DMF), anhydrous dimethyl sulfoxide (DMSO), trimethylaluminum (TMA) solution (2.0 M in toluene), and toluene (anhydrous, 99.8%) were purchased from Sigma-Ardrich. HCl (32 % in H2O) was obtained from Fisher Scientific.

[0563] 2. Preparation of CsPbBr3 precursor solution

[0564] CsPbBr3 was prepared by dissolving CsBr and PbBr2 with a Cs:Pb molar ratio of 2:1 in a mixed solvent of DMF and DMSO with a volume ratio of 1:9 to obtain a perovskite solution of the desired composition, and mixing 0.3 M PbBr2 and the solution with a magnetic stirring bar at 40° C. for more than 60 minutes. The solution was filtered using a PTFE filter (pore size 0.45 μm).

[0565] 3. Add TMA to the CsPbBr3 precursor solution

[0566] Add trimethylaluminum (TMA) solutions of different concentrations to the prepared CsPbBr3 precursor solution in a nitrogen-protected glove box. Mix the solution with a vortex mixer for 1 minute and then let it stand in the glove box for 10 minutes. Finally, filter the mixed solution with a PTFE filter (pore size 0.45 μm).

[0567] 4. CsPb(Br 1-x Cl x )3 Preparation of precursor solution

[0568] CsPb(Br) was prepared by changing the molar ratio of CsBr and CsCl and using PbBr2 and PbCl2 in the same molar ratio according to the stoichiometric amount. 1-x Cl x )3. For example, 1.490 g (7 mmol) of CsBr and 0.504 g (3 mmol) of CsCl were used to prepare CsPb(Br 0.7 Cl 0.3 )3, dissolved in 5mL deionized (DI) water, the solution was mixed into a clear solution with a vortex mixer. 2.569g (7mmol) of PbBr2 (Aldrich, ≥98%) and 0.834g (3mmol) of PbCl2 were dissolved in 8.82mL DMF and 1.68mL HBr (48wt%, ≥99.99%) and 3.15mL DMF and 1.35mL HCl (32%) at 100°C, respectively, with a magnetic stirring bar, the PbBr2 solution and the PbCl2 solution were mixed for 10min and 5min, and then at 18-20°C, the two solutions were mixed for 5min with a magnetic stirring bar.

[0569] CsBr 0.7 Cl 0.3 The aqueous solution was slowly added to the Pb(Br 0.7 Cl 0.3 )2 solution while stirring with a magnetic stirring bar at 18-20°C. To a certain extent, a bright yellow precipitate appears in the solution. Add 10mL of ethanol (Aldrich: laboratory reagent, 96%) to the solution containing the precipitate and mix with a vortex mixer for 10-20 seconds. Take out the precipitate and place it on an α-cellulose filter paper (Advantec), wash it several times with ethanol, and then dry it in a vacuum oven at 70°C for 10 hours. The prepared powder is dissolved in DMSO to obtain a perovskite solution of the desired composition, and 0.2M PbX2 and the solution are mixed with a magnetic stirring bar at 40°C for more than 60 minutes. Filter the solution with a PTFE filter (pore size 0.45μm).

[0570] 5. Preparation of thin films

[0571] The perovskite precursor solution was applied onto a glass substrate by spin coating at 3000 rpm (acceleration 500 rpm) for 50 s in a normal laboratory atmosphere (18-20 °C, humidity 40-60%), and then the perovskite film was annealed at 100 °C for 5 min in the same dry atmosphere.

[0572] For the TMA-solvent quenching method, 80 μL of the precursor solution was spin-coated on each substrate, and 10 s before the end of the spin-coating process, the substrate was quenched with 200 μL of TMA-mixed antisolvent by spinning at 3000 rpm (acceleration 500 rpm) for 30 s. Afterwards, the perovskite film was annealed at 100 °C for 5 min in the same dry atmosphere.

[0573] All film samples were coated with polymethyl methacrylate (PMMA, 20 mg / mL in chlorobenzene) to prevent moisture from air.

[0574] 6. Preparation of Nanocrystals

[0575] CsPbBr3 NCs were synthesized as previously reported by Protesescu et al. with some modifications. Typically, PbBr2 (1 g) (TCI), oleic acid (5 mL), oleylamine (5 mL), and ODE (50 mL) were all mixed, stirred in a 500 mL round-bottom flask, and degassed under vacuum at 120 °C for 1-2 h until PbBr2 was completely dissolved. The flask was then filled with N2 and maintained under a constant N2 flow while the temperature was set to 170 °C. The previously prepared Cs-oleate (7.5 mL) precursor, preheated to 100 °C, was rapidly injected into the reaction mixture. The flask was immersed in an ice bath and 20 mL of anhydrous toluene was added to stop and quench the reaction immediately (approximately 10 seconds after injection).

[0576] 7. Preparation of Nanocrystal Films Dispersed in PMMA and PS

[0577] The nanocrystal dispersion was added to polymethyl methacrylate (PMMA, 200 mg / mL in toluene) and polystyrene (PS, 200 mg / mL in toluene) to prepare thin films of polymer matrix. The polymer mixed nanocrystal solution was coated on a glass substrate using a doctor blade method.

[0578] 8. Encapsulation of PVB and EVA nanocrystalline films

[0579] Polyvinyl butyral (PVB) and ethylene vinyl acetate (EVA) are used as barrier films to block the nanocrystals. The barrier films are embedded between the glass where the nanocrystals are deposited and the top cover glass for encapsulation.

[0580] 9. Characterization

[0581] The UV-visible absorption spectra were measured using a commercial spectrophotometer (Varian Cary 300UV-Vis, USA). Photoluminescence (PL) spectra were recorded on a commercial spectrofluorimeter (Horiba, Fluorolog) using an excitation wavelength of 365 nm and a slit width of 3 mm. A 405 nm CW laser (RLTMDL-405, Roithner Lasertechnik GmbH) was used to illuminate the sample in an integrating sphere (Oriel Instruments 70682NS), and a fiber-coupled detector (Ocean OpticsMayaPro) was used to collect laser scattering and PL to determine the photoluminescence quantum yield (PLQY) value. PLQY calculations were performed using existing techniques. The laser intensity was adjusted using an optical density filter. The full spectrum of the Atlas SUNTEST XLS+ (1700 W air-cooled xenon lamp) simulated AM1.5, 76 mA cm -2 Stability test was performed under irradiance. The chamber temperature was about 60-70°C. The pulse frequency of the light source was 100Hz.

Claims

1. A method for producing a stable crystalline A / M / X material, wherein the stable crystalline A / M / X material comprises formula [Z] p O q Oxide and formula [A] a [M] b [X] c A compound wherein The stable crystalline A / M / X material is a polycrystalline material, wherein the polycrystalline material comprises a material having the formula [A] a [M] b [X] c A plurality of crystallites and a plurality of grain boundaries between the crystallites of a compound of formula [Z] p O q The oxides are distributed along the grain boundaries, in: [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV, wherein each element Z is selected from Al, Si, Zr, Ga, Ba, Nb, Mg, Y, Ti, Ni and Zn; p and q are positive numbers; [A] comprises one or more A cations, each of which is selected from an alkali metal cation; or C 1-10 Alkyl ammonium ion, C 2-10 Alkenyl ammonium ion, iminium ion, C 1-10 Alkyl iminium ion, C 3-10 Cycloalkylammonium ions and C 3-10 Cycloalkyliminium ion; the above C 1-10 Alkyl ammonium ion, C 2-10 Alkenyl ammonium ion, iminium ion, C 1-10 Alkyl iminium ion, C 3-10 Cycloalkylammonium ions and C 3-10 Each cation in the cycloalkyliminium ion is unsubstituted or is selected from amino, C 1-6 Alkylamino, imino, C 1-6 Alkyl imine, C 1-6 Alkyl, C 2-6 Alkenyl, C 3-6 Cycloalkyl and C 6-12 One or more substituents in the aryl group are substituted; [M] includes one or more M cations, each of which is selected from Li + 、Na + , K + , Rb + , Cs + , Cu + 、Ag + 、Au + , Hg + , 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+ 、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] includes one or more X anions, each of which is selected from F - , Cl - Br - and I - ; a is an integer from 1 to 6; b is an integer from 1 to 6; and c is an integer from 1 to 18, The method comprises treating the following substances with an oxide precursor comprising element Z: (a) an A precursor comprising an A cation; and (b) M precursor including M cation.

2. The method according to claim 1, wherein: The A precursor, the M precursor, and the oxide precursor are in solution.

3. The method according to claim 1 or 2, wherein: The A precursor and the M precursor are present in a first solution, and the first solution includes the A precursor, the M precursor, and a first solvent.

4. The method according to claim 3, wherein: The first solvent is an organic solvent.

5. The method according to claim 3, wherein: The first solvent is one of dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone or a mixture thereof.

6. The method according to claim 1 or 2, wherein: The oxide precursor is present in a second solution, and the second solution includes the oxide precursor and a second solvent.

7. The method according to claim 6, wherein: Formula [A] a [M] b [X] c The compound is insoluble in the second solvent.

8. The method according to claim 6, wherein: The second solvent is one of toluene, chlorobenzene, dichlorobenzene, anisole, methyl acetate, ethyl acetate, diethyl ether and chloroform.

9. The method according to claim 1 or 2, wherein: The treatment of the A precursor and the M precursor with the oxide precursor is performed in the presence of water.

10. The method according to claim 1 or 2, wherein: The method includes disposing the A precursor and the M precursor on a substrate before treating the A precursor and the M precursor with the oxide precursor.

11. The method according to claim 1 or 2, wherein: The elements Z are each selected from Al, Zr or Si.

12. The method according to claim 1 or 2, wherein: The element Z is each Al.

13. The method according to claim 1 or 2, wherein: A cations are each selected from Cs + , Rb + , one or more of methylammonium ion, ethylammonium ion, propylammonium ion, butylammonium ion, pentylammonium ion, hexylammonium ion, heptylammonium ion, octylammonium ion, formamidinium ion, benzylammonium ion, phenethylammonium ion, benzylammonium ion, naphthylmethylammonium ion and guanimine ion; and / or The M cations are each selected from the following metal or metalloid cations: Cu + 、Ag + 、Au + Sn 2+ , Pb 2+ , Cu 2+ ,Ge 2+ 、Ni 2+ 、Bi 3+ and Sb 3+ ; and / or The X anions are each selected from Cl - or Br - .

14. The method according to claim 1 or 2, wherein: [A] comprises two or more different A cations; and / or [X] comprises two or more different X anions; and / or The A precursor comprises the A cation or a halide salt of one of the A cations; and / or The M precursor includes the M cation or a halide salt of one of the M cations.

15. The method according to claim 1 or 2, wherein: The oxide precursor comprises one or more compounds of the formula ZR n A compound; wherein n is a number from 1 to 6; and R is independently selected from substituted C 1-10 Alkyl, C 2-10 Alkenyl, C 3-10 Cycloalkyl, C 1-10 Alkoxy, C 2-10 alkenyloxy, hydride and halide; or selected from unsubstituted C 1-10 Alkyl, C 2-10 Alkenyl, C 3-10 Cycloalkyl, C 1-10 Alkoxy, C 2-10 Alkenyloxy, hydride and halide.

16. The method according to claim 15, wherein: R is methyl, and n is 3.

17. The method according to claim 1 or 2, wherein: The oxide precursor is trimethylaluminum.

18. The method according to claim 1 or 2, wherein: The one or more A cations are monovalent cations, and the one or more M cations are divalent cations.

19. The method according to claim 1 or 2, wherein: The formula [A] a [M] b [X] c The compound is a compound of formula [A][M][X]3.

20. The method according to claim 1 or 2, wherein: The method further comprises removing any solvent present from the stable crystalline A / M / X material.

21. The method according to claim 1 or 2, wherein: The method is performed in the absence of aliphatic ligands.

22. The method according to claim 1 or 2, wherein: The stable crystalline A / M / X material comprises the formula [A] a [M] b [X] c A crystal of a compound having the formula [Z] on its entire surface p O q of the oxide coating.

23. A product obtained by and / or obtainable by the method of claim 1.

24. A stable crystalline A / M / X material, comprising formula [A] a [M] b [X] c A crystal of a compound having the formula [Z] on its entire surface p O q An oxide coating layer, wherein: [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV, wherein each element Z is selected from Al, Si, Zr, Ga, Ba, Nb, Mg, Y, Ti, Ni and Zn; p and q are positive numbers; [A] comprises one or more A cations, each of which is selected from an alkali metal cation; or C 1-10 Alkyl ammonium ion, C 2-10 Alkenyl ammonium ion, iminium ion, C 1-10 Alkyl iminium ion, C 3-10 Cycloalkylammonium ions and C 3-10 Cycloalkyliminium ion; the above C 1-10 Alkyl ammonium ion, C 2-10 Alkenyl ammonium ion, iminium ion, C 1-10 Alkyl iminium ion, C 3-10 Cycloalkylammonium ions and C 3-10 Each cation in the cycloalkyliminium ion is unsubstituted or is selected from amino, C 1-6 Alkylamino, imino, C 1-6 Alkyl imine, C 1-6 Alkyl, C 2-6 Alkenyl, C 3-6 Cycloalkyl and C 6-12 One or more substituents in the aryl group are substituted; [M] includes one or more M cations, each of which is selected from Li + 、Na + , K + , Rb + , Cs + , Cu + 、Ag + 、Au + , Hg + , 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+ 、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] includes one or more X anions, each of which is selected from F - , Cl - Br - and I - ; a is an integer from 1 to 6; b is an integer from 1 to 6; and c is an integer from 1 to 18, wherein the A / M / X material is a polycrystalline material including the crystals, wherein at least a portion of the oxide capping layer is located at crystal grain boundaries.

25. The stable crystalline A / M / X material of claim 24, wherein: (a) the formula [A] a [M] b [X] c The compound comprises the at least one element Z as an impurity; and / or (b) the stable crystalline A / M / X material is substantially free of aliphatic ligands; and / or (c) p is 1 to 3 and q is 1 to 8; and / or (d) the formula [A] a [M] b [X] c The compound is a compound of formula [A][M][X]3; and / or (e) [A] comprises two or more A cations; and / or (f) The crystals have a diameter of at least 50 nm.

26. A stable crystalline A / M / X material, wherein the stable crystalline A / M / X material is a polycrystalline material, wherein the polycrystalline material comprises a compound having the formula [A] a [M] b [X] c A plurality of crystallites of a compound and a plurality of grain boundaries between the crystallites, wherein Formula [Z] p O q The oxides are distributed along the grain boundaries, where [Z] comprises at least one element Z capable of forming an oxide having a band gap of at least 3 eV, wherein each element Z is selected from Al, Si, Zr, Ga, Ba, Nb, Mg, Y, Ti, Ni and Zn; p and q are positive numbers; [A] comprises one or more A cations, each of which is selected from an alkali metal cation; or C 1-10 Alkyl ammonium ion, C 2-10 Alkenyl ammonium ion, iminium ion, C 1-10 Alkyl iminium ion, C 3-10 Cycloalkylammonium ions and C 3-10 Cycloalkyliminium ion; the above C 1-10 Alkyl ammonium ion, C 2-10 Alkenyl ammonium ion, iminium ion, C 1-10 Alkyl iminium ion, C 3-10 Cycloalkylammonium ions and C 3-10 Each cation in the cycloalkyliminium ion is unsubstituted or is selected from amino, C 1-6 Alkylamino, imino, C 1-6 Alkyl imine, C 1-6 Alkyl, C 2-6 Alkenyl, C 3-6 Cycloalkyl and C 6-12 One or more substituents in the aryl group are substituted; [M] includes one or more M cations, each of which is selected from Li + 、Na + , K + , Rb + , Cs + , Cu + 、Ag + 、Au + , Hg + , 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+ 、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] includes one or more X anions, each of which is selected from F - , Cl - Br - and I - ; a is an integer from 1 to 6; b is an integer from 1 to 6; and c is an integer of 1-18.

27. The stable crystalline A / M / X material of claim 26, wherein: (a) the formula [A] a [M] b [X] c The compound comprises the at least one element Z as an impurity; and / or (b) the stable crystalline A / M / X material is substantially free of aliphatic ligands; and / or (c) p is 1 to 3 and q is 1 to 8; and / or (d) the formula [A] a [M] b [X] c The compound is a compound of formula [A][M][X]3; and / or (e) [A] comprises two or more A cations; and / or (f) The crystals have a diameter of at least 50 nm.

28. A coarse-grained powder comprising a stable crystalline A / M / X material as defined in claim 26.

29. A thin film comprising the stable crystalline A / M / X material as defined in claim 26.

30. An optoelectronic device comprising the stable crystalline A / M / X material as defined in claim 26, the coarse-grained powder as defined in claim 28 or the thin film as defined in claim 29.

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