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 light-responsive LED (Light Emitting Diode) based on a GaN/CsPbBr.sub.xI.sub.3-x heterojunction, a preparation method and an application thereof are provided. The light-responsive LED consists of a GaN base layer on a sapphire substrate, an all-inorganic perovskite CsPbBr.sub.xI.sub.3-x film, an indium electrode and a carbon electrode, forming an In/GaN/CsPbBr.sub.xI.sub.3-x/C structure, wherein: in the CsPbBr.sub.xI.sub.3-x film, 0<x<3; the all-inorganic perovskite CsPbBr.sub.xI.sub.3-x film and the indium electrode are arranged on the GaN base layer in parallel; and the carbon electrode is arranged on the all-inorganic perovskite CsPbBr.sub.xI.sub.3-x film. The CsPbBr.sub.xI.sub.3-x film is prepared through a low-temperature anti-solvent method. The prepared LED device is able to realize integration of self-powered visible detection and visible luminescence, and able to work as a transmitting terminal or a receiving terminal in visible light wireless communication, which solves a difficult problem of backward communication in visible light wireless communication technology.

Embodiments of the present disclosure generally describe scintillation materials, including colloidal scintillation materials and solid scintillation materials, methods of preparing the scintillation materials, applications of the scintillation materials, methods of using the scintillation materials, and the like.

A perovskite luminescent nanocrystal has a chemical formula represented by: Cs.sub.4BX.sub.6, wherein B includes one or more selected from the group consisting of Ge, Pb, Sn, Sb, Bi, Cu, and Mn, and X includes one or more selected from the group consisting of Cl, Br, and I, wherein the Cs.sub.4BX.sub.6 perovskite luminescent nanocrystal has a pure phase, and a molar ratio of Cs to B (Cs/B) in the Cs.sub.4BX.sub.6 perovskite luminescent nanocrystal is greater than 1 and less than 4.

A light-responsive LED (Light Emitting Diode) based on a GaN/CsPbBr.sub.xI.sub.3-x heterojunction, a preparation method and an application thereof are provided. The light-responsive LED consists of a GaN base layer on a sapphire substrate, an all-inorganic perovskite CsPbBr.sub.xI.sub.3-x film, an indium electrode and a carbon electrode, forming an In/GaN/CsPbBr.sub.xI.sub.3-x/C structure, wherein: in the CsPbBr.sub.xI.sub.3-x film, 0<x<3; the all-inorganic perovskite CsPbBr.sub.xI.sub.3-x film and the indium electrode are arranged on the GaN base layer in parallel; and the carbon electrode is arranged on the all-inorganic perovskite CsPbBr.sub.xI.sub.3-x film. The CsPbBr.sub.xI.sub.3-x film is prepared through a low-temperature anti-solvent method. The prepared LED device is able to realize integration of self-powered visible detection and visible luminescence, and able to work as a transmitting terminal or a receiving terminal in visible light wireless communication, which solves a difficult problem of backward communication in visible light wireless communication technology.

An oxychloride infrared nonlinear optical crystal and the preparation method and use thereof, the optical crystal has a general chemical formula of Pb.sub.2+xOCl.sub.2+2x, therein 0<x<0.139 or 0.141<x<0.159 or 0.161<x0.6. The crystal is non-centrosymmetric, belongs to orthonormal system with space group of Fmm2, cell parameter is a=35.4963(14)0.05 , b=5.8320(2)0.05 , c=16.0912(6)0.05 . The crystal is prepared by high temperature melt method or flux method. The crystal has a strong second harmonic generation efficiency of 4 times that of KDP (KH.sub.2PO.sub.4) tested by Kurtz method, it is phase machable, transparent in the range of 0.34-7 m. The laser damage threshold is 10 times that of the current commercial infrared nonlinear optical crystal AgGaS.sub.2. No crystalline water exists in lead oxychloride, and it is stable in the air and has good thermal stability.

An oxychloride infrared nonlinear optical crystal and the preparation method and use thereof, the optical crystal has a general chemical formula of Pb.sub.2+xOCl.sub.2+2x, therein 0<x<0.139 or 0.141<x<0.159 or 0.161<x0.6. The crystal is non-centrosymmetric, belongs to orthonormal system with space group of Fmm2, cell parameter is a=35.4963(14)0.05 , b=5.8320(2)0.05 , c=16.0912(6)0.05 . The crystal is prepared by high temperature melt method or flux method. The crystal has a strong second harmonic generation efficiency of 4 times that of KDP (KH.sub.2PO.sub.4) tested by Kurtz method, it is phase machable, transparent in the range of 0.34-7 m. The laser damage threshold is 10 times that of the current commercial infrared nonlinear optical crystal AgGaS.sub.2. No crystalline water exists in lead oxychloride, and it is stable in the air and has good thermal stability.

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 pre-cursors 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.

A formulation for use in the preferential formation of thin films of a perovskite material AMX.sub.3 with a certain required crystalline structure, wherein said formulation comprises two or more compounds which between them comprise one or more first organic cations A; one or more metal cations M; one or more second cations A; one or more first anions X and one or more second anions X.

The present invention relates to a method for producing core-shell nanocrystals consisting of a metal-containing nanocrystal core and a shell layer comprising at least one metal oxide material having variable shell thicknesses, and use of the core-shell nanocrystals for different applications.