Methods are provided for making halide perovskite thin films. The method may include forming a pattern of islands of a nucleation promoter material onto a substrate; applying onto the substrate and islands a solution which includes a halide perovskite or precursors thereof, to form a coated substrate; and drying the coated substrate to form a crystalline halide perovskite film. Halide perovskite thin films, which may be made by these methods, and LEDs including these films are also provided.

The present disclosure pertains to a color filter for a display device, which has at least one color filter element for generating a predefined color in response to incident light, wherein the at least one color filter element includes a Perovskite material.

Disclosed are processes for preparing hybrid perovskite quantum dots and the resulting hybrid perovskite quantum dots and uses thereof. Such quantum dots are useful as semiconductors in devices such as solar cells and light-emitting diodes.

A thin film includes a luminescent compound represented by Formula 1 and a random copolymer, wherein the random copolymer includes a first repeating unit including at least one aromatic ring, and a second repeating unit including a heteroatom including at least one lone pair of electrons,
[A].sub.n[Q].sub.m[X].sub.l  Formula 1
wherein, in Formula 1, A is a monovalent organic cation, a monovalent inorganic cation, or a combination thereof, Q is a divalent metal cation, a divalent metalloid cation, or a combination thereof, X is at least one monovalent halogen ion, n is an integer from 1 to 3, m is an integer from 1 to 2, and l is an integer from 1 to 5.

A compound has a perovskite type crystal structure containing A which is a monovalent cation, B which is a metal ion, and X which is a halide ion as components. The perovskite type crystal structure has a unit cell volume of 0.2000 nm.sup.3 or more and 0.2150 nm.sup.3 or less, an ionic radius of B of 0.7 Å or more and 1.4 Å or less, and an ionic radius of X of 0.5 Å or more and 2.5 Å or less.

An A/M/X crystalline material, a photovoltaic device, and preparation methods thereof are provided. The photovoltaic device includes a photoactive crystalline material layer. The photoactive crystalline material layer includes a penetrating crystal, where the penetrating crystal is a crystal penetrating through the photoactive crystalline material layer, and a percentage p of a quantity of penetrating crystals in a total quantity of crystals of the photoactive crystalline material layer is ≥80%. The photoactive crystalline material layer includes a backlight side and a backlight crystal, where the backlight crystal is a crystal exposed to the backlight side and has a backlight crystal face exposed to the backlight side. At least one region of the backlight side has an average flatness index R.sub.avg being ≤75.

An H.sub.2S sensor includes at least one acoustic wave transducer and a film having a polymer matrix. The polymer matrix includes carboxylate functional groups and lead or zinc cations. The film may have a thickness of between a hundred nanometres and a 2 microns The H.sub.2S sensor optionally includes an antenna to remotely interrogate the H.sub.2S sensor.

Provided herein is a method of preparing carbon-graphene-lead composite particles, comprising the steps of forming a dispersion of lead particles, graphene particles and cellulose in an aqueous solution, spray drying the dispersion to aggregate the lead particles, graphene particles and cellulose to form cellulose-graphene-lead composite particles, and heating the cellulose-graphene-lead composite particles, to carbonize the cellulose to result in the formation of the carbon-graphene-lead composite particles.

A method for forming CsPbBr.sub.3 perovskite nanocrystals into a two-dimensional (2D) nanosheet includes providing CsPbBr.sub.3 perovskite nanocrystals; mixing the CsPbBr.sub.3 perovskite nanocrystals into a mixture of a first solvent and a second solvent, to form a solution of the CsPbBr.sub.3 perovskite nanocrystals, the first solvent, and the second solvent; and forming an optoelectronic device by patterning the CsPbBr.sub.3 perovskite nanocrystals into a nanosheet, between first and second electrodes. The first solvent is selected to evaporate before the second solvent.

A flexible photovoltaic device is provided. The flexible photovoltaic device includes a flexible inorganic halide perovskite. The flexible inorganic halide perovskite is free of organic components, has a thickness of greater than or equal to about 1 μm to less than or equal to about 1 nm, and has an average grain size of less than or equal to about 500 nm.