A composition consisting essentially of a perovskite crystalline structure includes ions of a first metal M1 which occupies an A-site of the perovskite crystalline structure and ions of a second metal M2 which occupies a B-site of the perovskite crystalline structure. M2 has two oxidation states capable of forming a redox couple suitable for reversibly catalyzing an oxygen reduction reaction (ORR) and an oxygen evolution reaction (OER). The composition also includes ions of a third metal M3 at least a portion of which substitutes for M1 in the A-site of the perovskite crystalline structure, and at least a portion of which optionally also substitutes for M2 in the B-site of the perovskite crystalline structure. At least some of the ions of M3 have a different oxidation state to the ions of M1. The composition also includes atoms of an element X, which is a chalcogen.

The perovskite compound according to the invention has a cubic perovskite structure, has high catalytic activity in oxygen reduction and evolution reactions, and has excellent durability, and thus, can be used as a catalyst of electrochemical devices, particularly as a fuel cell catalyst.

Disclosed is a method of exchanging the anions of inorganic halide perovskite nanoparticles using cationic effect. More particularly, the method is a cation effect-based anion exchange method of being capable of improving optical stability while controlling the optical band energy of CsPbBr.sub.3 perovskite nanoparticles at room temperature. According to an embodiment of the present disclosure, a cation-anion pair suitable for anion exchange and stability improvement can be provided.

A perovskite material that has a perovskite crystal lattice having a formula of C.sub.xM.sub.yX.sub.z, where x, y, and z, are real numbers, and 1,4-diammonium butane cation cations disposed within or at a surface of the perovskite crystal lattice. C comprises one or more cations selected from the group consisting of Group 1 metals, Group 2 metals, ammonium, formamidinium, guanidinium, and ethene tetramine. M comprises one or more metals each selected from the group consisting of Be, Mg, Ca, Sr, Ba, Fe, Cd, Co, Ni, Cu, Ag, Au, Hg, Sn, Ge, Ga, Pb, In, Tl, Sb, Bi, Ti, Zn, Cd, Hg, and Zr and combinations thereof. X comprises one or more anions each selected from the group consisting of halides, sulfides, selenides, and combinations thereof.

A perovskite material that has a perovskite crystal lattice having a formula of C.sub.xM.sub.yX.sub.z, and alkyl polyammonium cations disposed within or at a surface of the perovskite crystal lattice; wherein x, y, and z, are real numbers; C comprises one or more cations selected from the group consisting of Group 1 metals, Group 2 metals, ammonium, formamidinium, guanidinium, and ethene tetramine; M comprises one or more metals each selected from the group consisting of Be, Mg, Ca, Sr, Ba, Fe, Cd, Co, Ni, Cu, Ag, Au, Hg, Sn, Ge, Ga, Pb, In, Tl, Sb, Bi, Ti, Zn, Cd, Hg, and Zr, and combinations thereof and X comprises one or more anions each selected from the group consisting of halides, pseudohalides, chalcogenides, and combinations thereof.

There is provided a protein-halide perovskite nanocrystal (p-HPNC) comprising: a crystalline core of halide perovskites and an outer layer made of protein surrounding the crystalline core. The protein has a net positive electric charge at a pH of 3 or less in its free state. The protein is linked to the surface of the crystalline core, and the halide perovskites have a formula ABX.sub.3, where A is a monovalent cation, B is a divalent cation, and X is a monovalent halide anion.

A luminophore may have the general formula A.sub.xM.sub.yX.sub.z:RE. A may be selected from the group of the trivalent cations. M may be selected from the group of the trivalent cations and includes at least two elements from the following group: Ga, Sc, Al, In, Sb, Bi, As, and Lu. X may be selected from the group of the divalent anions. RE may be a dopant and may be selected from the group formed by the following elements and the combinations of the following elements: Ni, Mn, Cr, Co, Fe, and Sn, where

0.8≤x≤1.2,

0.8≤y≤1.2 and

2.7≤z≤3.3.

A process is also disclosed for producing a luminophore, an optoelectronic component, and an NIR spectrometer.

A nanoparticle cluster reduction method yields a new composition of matter including a large percentage (e.g., 75% or higher percentage) of primary nanoparticles in the new composition of matter. The particle reduction method reduces the size of nanoparticle clusters in material of the new composition of matter, allows particle reduction of specific nanoparticle cluster sizes, and allows particle reduction to primary nanoparticles. This new composition of matter can include a high permittivity and high resistivity dielectric compound. This new composition of matter, according to certain examples, has high permittivity, high resistivity, and low leakage current. In certain examples, the new composition of matter constitutes a dielectric energy storage device that is a battery with very high energy density, high operating voltage per cell, and an extended battery life cycle. An example method can include a controlled gas evolution reaction to reduce the size of nanoparticle clusters.

A thin film structure including a dielectric material layer and an electronic device to which the thin film structure is applied are provided. The dielectric material layer includes a compound expressed by ABO.sub.3, wherein at least one of A and B in ABO.sub.3 is substituted and doped with another atom having a larger atom radius, and ABO.sub.3 becomes A.sub.1-xA′.sub.xB.sub.1-yB′.sub.yO.sub.3 (where x>=0, y>=0, at least one of x and y≠0, a dopant A′ has an atom radius greater than A and/or a dopant B′ has an atom radius greater than B) through substitution and doping. A dielectric material property of the dielectric material layer varies according to a type of a substituted and doped dopant and a substitution doping concentration.

The present disclosure relates to a composition including a light-emitting perovskite compound (1) which includes constituent components A, B, and X, and a silazane or modified product thereof (2).