Abstract: The invention relates to a process for producing a crystalline A/M/X material, which crystalline A/M/X material comprises a compound of formula [A]a[M]b[X]c wherein: [A] comprises one or more A cations; [M] comprises one or more M cations which are metal or metalloid cations; [X] comprises one or more X anions; a is a number from 1 to 6; b is a number from 1 to 6; and c is a number from 1 to 18. The process is capable of producing crystalline A/M/X materials while precisely controlling their stoichiometry, leading to products with finely tunable optical properties such as peak emission wavelength. The invention also relates to process for producing a thin film comprising the crystalline A/M/X material of the invention, and to a thin film obtainable by the process of the invention. An optoelectronic device comprising the thin film is also provided.

Abstract: The present invention relates to a process for producing a layer of a crystalline A/M/X material, which crystalline A/M/X material comprises a compound of formula [A]a[M]b[X]c, wherein: [M] comprises one or more first cations, which one or more first cations are metal or metalloid cations; [A] comprises one or more second cations; [X] comprises one or more halide 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, wherein the process comprises disposing on a substrate a precursor composition comprising: (a) a first precursor compound comprising a first cation (M), which first cation is a metal or metalloid cation; and (b) a solvent, and wherein the solvent comprises: (i) a non-polar organic solvent which is a hydrocarbon solvent, a chlorohydrocarbon solvent or an ether solvent; and (ii) a first organic amine comprising at least three carbon atoms. Also described are compositions useful in the process of the invention.

Abstract: The present invention relates to a semiconductor device comprising a semiconducting material, wherein the semiconducting material comprises a compound comprising: (i) one or more first monocations [A]; (ii) one or more second monocations [BI]; (iii) one or more trications [BIII]; and (iv) one or more halide anions [X]. The invention also relates to a process for producing a semiconductor device comprising said semiconducting material. Also described is a compound comprising: (i) one or more first monocations [A]; (ii) one or more second monocations [BI] selected from Cu+, Ag+ and Au+; (iii) one or more trications [BIII]; and (iv) one or more halide anions [X].

Abstract: The present invention relates to a method for preparing a stabilised crystalline A/M/X material comprising an oxide of formula [Z]pOq and a compound of formula [A]a[M]b[X]c, wherein [Z] comprises at least one element Z capable of forming an oxide with 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. Often, the stabilised crystalline A/M/X material is a perovskite. The invention also provides a stabilised crystalline A/M/X material, which can be produced by the process of the invention. The invention further provides materials and devices containing the stabilised crystalline A/M/X material of the invention.

Abstract: The present invention relates to a method for preparing a stabilised crystalline A/M/X material comprising an oxide of formula [Z]pOq and a compound of formula [A]a[M]b[X]c, wherein [Z] comprises at least one element Z capable of forming an oxide with 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. Often, the stabilised crystalline A/M/X material is a perovskite. The invention also provides a stabilised crystalline A/M/X material, which can be produced by the process of the invention. The invention further provides materials and devices containing the stabilised crystalline A/M/X material of the invention.

Abstract: The present invention relates to a semiconductor device comprising a semiconducting material, wherein the semiconducting material comprises a compound comprising: (i) one or more first monocations [A]; (ii) one or more second monocations [BI]; (iii) one or more trications [BIII]; and (iv) one or more halide anions [X]. The invention also relates to a process for producing a semiconductor device comprising said semiconducting material. Also described is a compound comprising: (i) one or more first monocations [A]; (ii) one or more second monocations [BI] selected from Cu+, Ag+ and Au+; (iii) one or more trications [BIII]; and (iv) one or more halide anions [X].

Abstract: The invention relates to a process for producing a crystalline A/M/X material, which crystalline A/M/X material comprises a compound of formula [A]a[M]b[X]c wherein: [A] comprises one or more A cations; [M] comprises one or more M cations which are metal or metalloid cations; [X] comprises one or more X anions; a is a number from 1 to 6; b is a number from 1 to 6; and c is a number from 1 to 18. The process is capable of producing crystalline A/M/X materials while precisely controlling their stoichiometry, leading to products with finely tunable optical properties such as peak emission wavelength. The invention also relates to process for producing a thin film comprising the crystalline A/M/X material of the invention, and to a thin film obtainable by the process of the invention. An optoelectronic device comprising the thin film is also provided.

Abstract: A photovoltaic device comprises plural layers separated into plural cells, each comprising a region of a photoactive layer and electrodes on opposite sides thereof. Each of the regions of the photoactive layer are formed comprising a first part that comprises photoactive material and a second part that is not photoactive and that has a greater transmittance of visible light than the light absorbing photoactive material, in pre-selected locations, or in a pre-selected distribution of locations, across the region of the photoactive layer. One of the first and second parts are located in plural separate areas within the other of the first and second parts. The transparency of the photovoltaic device is increased by the transmission of light through the second part that is not photoactive.

Abstract: The invention relates to perovskite compounds which have surprisingly good emission properties, particularly photoluminescent emission properties, in the blue region of the visible spectrum. These perovskites contain a mixture of cations or a mixture of halides, or both. The invention also relates to a photoactive material containing the perovskite species of the invention; to an optoelectronic device containing the photoactive material of the invention; to a method of producing blue light; and to the use of the photoactive material of the invention to emit blue light or as a phosphor.

Abstract: The invention provides an optoelectronic device comprising a photoactive region, which photoactive region comprises: an n-type region comprising at least one n-type layer; a p- type region comprising at least one p-type layer; and, disposed between the n-type region and the p-type region: a layer of a perovskite semiconductor without open porosity. The perovskite semiconductor is generally light-absorbing. In some embodiments, disposed between the n-type region and the p-type region is: (i) a first layer which comprises a scaffold material, which is typically porous, and a perovskite semiconductor, which is typically disposed in pores of the scaffold material; and (ii) a capping layer dis -posed on said first layer, which capping layer is said layer of a perovskite semiconductor without open porosity, wherein the perovskite semiconductor in the capping layer is in contact with the perovskite semiconductor in the first layer.

Abstract: The invention provides an optoelectronic device comprising a photoactive region, which photoactive region comprises: an n-type region comprising at least one n-type layer; a p-type region comprising at least one p-type layer; and, disposed between the n-type region and the p-type region: a layer of a perovskite semiconductor without open porosity. The perovskite semiconductor is generally light-absorbing. In some embodiments, disposed between the n-type region and the p-type region is: (i) a first layer which comprises a scaffold material, which is typically porous, and a perovskite semiconductor, which is typically disposed in pores of the scaffold material; and (ii) a capping layer disposed on said first layer, which capping layer is said layer of a perovskite semiconductor without open porosity, wherein the perovskite semiconductor in the capping layer is in contact with the perovskite semiconductor in the first layer.

Abstract: The invention provides an optoelectronic device comprising a photoactive region, which photoactive region comprises: an n-type region comprising at least one n-type layer; a p-type region comprising at least one p-type layer; and, disposed between the n-type region and the p-type region: a layer of a perovskite semiconductor without open porosity. The perovskite semiconductor is generally light-absorbing. In some embodiments, disposed between the n-type region and the p-type region is: (i) a first layer which comprises a scaffold material, which is typically porous, and a perovskite semiconductor, which is typically disposed in pores of the scaffold material; and (ii) a capping layer disposed on said first layer, which capping layer is said layer of a perovskite semiconductor without open porosity, wherein the perovskite semiconductor in the capping layer is in contact with the perovskite semiconductor in the first layer.

Abstract: The invention provides an optoelectronic device comprising a photoactive region, which photoactive region comprises: an n-type region comprising at least one n-type layer; a p-type region comprising at least one p-type layer; and, disposed between the n-type region and the p-type region: a layer of a perovskite semiconductor without open porosity. The perovskite semiconductor is generally light-absorbing. In some embodiments, disposed between the n-type region and the p-type region is: (i) a first layer which comprises a scaffold material, which is typically porous, and a perovskite semiconductor, which is typically disposed in pores of the scaffold material; and (ii) a capping layer disposed on said first layer, which capping layer is said layer of a perovskite semiconductor without open porosity, wherein the perovskite semiconductor in the capping layer is in contact with the perovskite semiconductor in the first layer.

Abstract: The invention relates to an optoelectronic device comprising: (a) a layer comprising a crystalline A/M/X material, wherein the crystalline A/M/X material comprises a compound of formula: [A]a[M]b[X]c wherein: [A] comprises one or more A cations; [M] comprises one or more M cations which are metal or metalloid cations; [X] comprises one or more X anions; a is a number from 1 to 6; b is a number from 1 to 6; and c is a number from 1 to 18; and (b) an ionic solid which is a salt comprising an organic cation and a counter anion. The invention also provides various processes for producing an ionic solid-modified film of the crystalline A/M/X material.

Abstract: The invention relates to a process for chemically etching the surface of a metal halide perovskite, the process comprising treating the metal halide perovskite with one or more multidentate ligands, wherein the one or more multidentate ligands comprise an organic compound or a salt thereof, which organic compound comprises three or more binding groups. A chemically etched metal halide perovskite, a process for producing a semiconductor device, a composition and a semiconductor device are also described.

Abstract: The present invention relates to an optoelectronic device comprising: (a) a substrate comprising at least one first electrode, which at least one first electrode comprises a first electrode material, and at least one second electrode, which at least one second electrode comprises a second electrode material; and (b) a photoactive material disposed on the substrate, which photoactive material is in contact with the at least one first electrode and the at least one second electrode, wherein the substrate comprises: a layer of the first electrode material; and, disposed on the layer of the first electrode material, a layer of an insulating material, which layer of an insulating material partially covers the layer of the first electrode material; and, disposed on the layer of the insulating material, the second electrode material, and wherein the photoactive material comprises a crystalline compound, which crystalline compound comprises: one or more first cations selected from metal or metalloid cations; one or m

Abstract: The invention provides a process for producing a passivated semiconductor, which process comprises treating a semiconductor with a passivating agent, wherein: the semiconductor comprises a crystalline compound comprising: (i) one or more first cations (A); (ii) one or more metal cations (M); and (iii) one or more anions (X); and the passivating agent comprises a compound comprising an oxygen-oxygen single bond. A composition and the use of a passivating agent are also provided.

Abstract: The invention relates to an optoelectronic material comprising a compound, wherein the compound comprises: (i) one or more cations, A; (ii) one or more first B cations, Bn+; (iii) one or more second B cations, Bm+; and (iv) one or more chalcogen anions, X; wherein the one or more first B cations, Bn+ are different from the one or more second B cations, Bm+; n represents the oxidation state of the first B cation and is a positive integer of from 1 to 7 inclusive; m represents the oxidation state of the second B cation and is a positive integer of from 1 to 7 inclusive; and n+m is equal to 8.

Abstract: The invention relates to an optoelectronic device comprising: (a) a layer comprising a crystalline A/M/X material, wherein the crystalline A/M/X material comprises a compound of formula: [A]a [M]b [X]c wherein: [A] comprises one or more A cations; [M] comprises one or more M cations which are metal or metalloid cations; [X] comprises one or more X anions; a is a number from 1 to 6; b is a number from 1 to 6; and c is a number from 1 to 18; and (b) an ionic liquid which is a salt comprising an organic cation and a counter anion, wherein the organic cation is present within the layer comprising the crystalline A/M/X material. The invention also relates to processes for producing an ionic liquid-modified film of a crystalline A/M/X material and a process for producing an optoelectronic device comprising an ionic-liquid modified film of a crystalline A/M/X material.

Abstract: The present invention relates to a semiconductor device comprising a semiconducting material, wherein the semiconducting material comprises a halometallate compound comprising: (a) cesium; (b) palladium; and (c) one or more halide anions [X]. The invention also relates to a layer comprising the semiconducting material. The invention further relates to a process for producing a halometallate compound of formula (IV): [A]2[MIV][X]6, which process uses a H[X] and a compound comprising a sulfoxide group.