A light converting nanoparticle represented by Chemical Formula 1,
AX.sub.xChemical Formula 1
wherein, in Chemical Formula 1, A comprises an alkaline metal element, an alkaline-earth metal element, or a combination thereof, X comprises a halogen element, and x is 1 or 2 and is selected such that Chemical Formula 1 is electrically neutral, and a dopant substituted for a portion of A, wherein the dopant comprises Tl.sup.+, In.sup.+, Pb.sup.2+, Bi.sup.3+, Ag.sup.+, Cu.sup.+, Eu.sup.2+, Mn.sup.2+, or a combination thereof, wherein a content of the dopant is less than 15 mole percent, based on a total moles of A, wherein the light converting nanoparticle has a particle diameter of less than or equal to about 100 nanometers, and the light converting nanoparticle has a structure, cubic structure, an orthorhombic structure, a rhombic dodecahedron structure, or a combination thereof.

In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, the disclosure, in one aspect, relates to compound Bi-poor perovskite crystals, methods for making the same, and ionizing and other electromagnetic radiation detectors constructed using the Bi-poor perovskite crystals. The Bi-poor perovskite crystals can be synthesized using melt-based growth methods and solution-based growth methods and contain no toxic heavy metals such as lead, cadmium, thallium, or mercury. Devices fabricated from the crystals maintain acceptable levels of performance over time. In some aspects, post-growth annealing can be used to improve the properties, including, but not limited to, room temperature resistivity and response to radiation.

A scintillation crystal can include a cesium halide that is co-doped with thallium and another element. In an embodiment, the scintillation crystal can include CsX:Tl, Me, where X represents a halogen, and Me represents a Group 5A element. In a particular embodiment, the scintillation crystal may have a cesium iodide host material, a first dopant including a thallium cation, and a second dopant including an antimony cation.

A light converting nanoparticle represented by Chemical Formula 1,

AX.sub.x Chemical Formula 1

wherein, in Chemical Formula 1, A comprises an alkaline metal element, an alkaline-earth metal element, or a combination thereof, X comprises a halogen element, and x is 1 or 2 and is selected such that Chemical Formula 1 is electrically neutral, and a dopant substituted for a portion of A, wherein the dopant comprises Tl.sup.+, In.sup.+, Pb.sup.2+, Bi.sup.3+, Ag.sup.+, Cu.sup.+, Eu.sup.2+, Mn.sup.2+, or a combination thereof, wherein a content of the dopant is less than 15 mole percent, based on a total moles of A, wherein the light converting nanoparticle has a particle diameter of less than or equal to about 100 nanometers, and the light converting nanoparticle has a structure, cubic structure, an orthorhombic structure, a rhombic dodecahedron structure, or a combination thereof.

A method of producing perovskite nanocrystalline particles using a liquid crystal includes a first operation for preparing a mixed solution including a first precursor compound, a second precursor compound, and a first solvent. a second operation for preparing a precursor solution by adding an organic ligand to the prepared mixed solution, a third operation for performing crystallization treatment after adding the prepared precursor solution to a reactor containing a liquid crystal, and a fourth operation for separating the perovskite nanocrystalline particles from the crystallized solution through a centrifugal separator.

Provided is a scintillator having a crystal containing CsI (cesium iodide) as a host material thereof and thallium (Tl) and bismuth (Bi), and a novel scintillator which maintains a high output and simultaneously can further enhance the afterglow characteristics. There is proposed a scintillator having a crystal containing CsI (cesium iodide) as a host material thereof and Tl, Bi and O, wherein the concentration a of Bi with respect to Cs in the crystal is 0.001 atomic ppma5 atomic ppm; and the ratio (a/b) of the concentration a of Bi with respect to Cs in the crystal to the concentration b of O with respect to I in the crystal is 0.00510.sup.4 to 20010.sup.4.

An afterglow property of cesium iodide:thallium (CsI:Tl), in which CsI is a host material and doped with thallium, is improved. It is possible to improve the afterglow property of a scintillator by doping a crystal material including CsI (cesium iodide), as a host material, and thallium (Tl), as a luminescent center, with bismuth (Bi).

Provided is a scintillator having a crystal containing CsI (cesium iodide) as a host material thereof and thallium (Tl) and bismuth (Bi), and a novel scintillator which maintains a high output and simultaneously can further enhance the afterglow characteristics. There is proposed a scintillator having a crystal containing CsI (cesium iodide) as a host material thereof and Tl, Bi and O, wherein the concentration a of Bi with respect to Cs in the crystal is 0.001 atomic ppma5 atomic ppm; and the ratio (a/b) of the concentration a of Bi with respect to Cs in the crystal to the concentration b of O with respect to I in the crystal is 0.00510.sup.4 to 20010.sup.4.

A semiconductor nanocrystal particle represented by Chemical Formula 1 and having a full width at half maximum (FWHM) of less than or equal to about 30 nanometers (nm) in the emission wavelength spectrum is provided:
A.sub.xA.sub.(3+x)D.sub.(2+)E.sub.(9+).Chemical Formula 1 In Chemical Formula 1, A is a first metal including Rb, Cs, or a combination thereof, A is an organic substance derived from an ammonium salt, an organic material derived from an organic ligand, or an organic material including a combination thereof, D is a second metal including Sb, Bi, or a combination thereof E is Cl, Br, I, or a combination thereof, 1<x3, 1<<1, 3+x>0, 1<<1, and 1<<1.

Described is a thin film comprising a Yb-doped double perovskite, wherein the double perovskite has the formula M.sub.2AYb.sub.xB.sub.(1-x)X.sub.6; wherein each occurrence of M independently represents Cs or Rb; A represents Ag or Cu; B represents Bi, In, Sb, or Ga; x has a value between 0.01 and 0.20; and each X independently represents F, Cl, Br, or I. Also described is a method of making the thin films. The thin film may be useful in photovoltaic devices.