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 provides a light valve containing ABX.sub.3 perovskite particles; more specifically is related to a light valve containing halide ABX.sub.3 perovskite particles that can control light transmittance. The preferable halide ABX.sub.3 perovskite particles in this invention consist of A being at least one of Cs.sup.+, CH3NH3.sup.+, and Rb.sup.+, B being at least one of Pb.sup.2+, Ge.sup.2+, and Sn.sup.2+, and X being at least one of Cl.sup., Br.sup., and I.sup.. This kind of halide ABX.sub.3 perovskite particles were suspended in a liquid suspension to make a light valve with a light transmittance control, which discloses a completely new application for ABX.sub.3 perovskite materials.

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.

Methods of growing large, free-standing single crystals of (FA.sub.xCs.sub.1-x)PbBr.sub.3 perovskites, where 0x<1, in solution using tertiary or ternary alkyl ammonium salts, weak organic acids, or a combination thereof are provided. By including the additives in a crystallization solution with perovskite precursors, larger single crystals can be grown by slow evaporation or inverse temperature crystallization than would possible in the absence of the additives under the same growth conditions.

The present invention relates to a process for the synthesis of B-site doped ABX.sub.3 perovskite nanocrystals. The process comprises the steps of loading non-halide precursors of A, B, and dopant in three neck flasks along with long chain acid and olefin, purging of the reaction mixture under heating, and finally injection of alkylammonium chloride stock solution in the reaction mixture at a desired temperature. Introducing transition metal such as Mn and other rare earths, etc., as dopants in the perovskite nanocrystals to induce a new optical window.

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 perovskite quantum dot preparation method and a perovskite quantum dot solution are provided. The preparation method may include: providing a first solution including caesium oleate, a second solution including lead halide and a third solution including DDAB; adding the first solution, the second solution and the third solution into a non-polar alkyl solution at a preset proportion and stifling to obtain a perovskite quantum dot solution; the perovskite quantum dot solution may include caesium-lead-halogen of pure phase. In this way, the present disclosure can easily obtain the perovskite quantum dot solution including caesium-lead-halogen of pure phase.

A main object of the present disclosure is to provide a cathode active material used for a fluoride ion battery, the cathode active material comprising: a first active material having a composition represented by Pb.sub.2xCu.sub.1+xF.sub.6, wherein 0x<2; and a second active material containing a Bi element and a F element.

Various embodiments disclosed related to organic or inorganic metal halide perovskites formed via cation exchange and photovoltaic applications thereof. The present invention provides a method of forming an organic or inorganic metal halide perovskite including cation exchanging a hydrocarbylammonium metal halide with a salt comprising an organic or inorganic cation that exchanges with the hydrocarbylammonium cation of the hydrocarbylammonium metal halide, to form the organic or inorganic metal halide perovskite.

The invention provides a material with perovskite-type structure having a formula selected from Formula I and Formula II. in which A represents one or more monovalent cations that can be selected from alkali metal ions, (organo)ammonium and (organo)phosphonium ions; A represents one or more divalent cations that can be selected from alkaline earth metal cations; A represents one or more trivalent cations that can be selected from lanthanide ions; a, b and c are each in the range of from 0 to 1, a+b+c=1; x=a+2b+3c; d is in the range of from 1 to 5, each of e, f and g are in the range of from 0 to 1. with the proviso that g is less than 1 in Formula I; e+f+g?1; y=2(e+f)+3g; each X in X and X2 is independently selected from the halogens; and h is in the range of from 0.0001 to 0.2. X2 is a dihalogen moiety, and can be the source of a valence band hole in the photovoltaic semiconducting material. The invention also relates to photovoltaic devices or a surface coating that comprises the material.