Light converting nanoparticle, method of making the light converting nanoparticle, and composition and optical film comprising the same

A method of making a light converting nanoparticle, the method comprising:

• adding a first precursor solution comprising a halogen element into a reaction vessel;
• adding a dopant comprising Tl+, In+, Pb2+, Ag+, Cu+, Eu2+, Mn2+, or a combination thereof to the reaction vessel;
• heating the reaction vessel to a selected temperature;
• and
• contacting the first precursor solution with a second precursor solution, the second precursor solution comprising an alkaline metal element, an alkaline-earth metal element, or a combination thereof to form the light converting nanoparticle,
• wherein the light converting nanoparticle comprises a compound represented by Chemical Formula 1,
• AXx Chemical Formula 1
• wherein, in Chemical Formula 1,
• A comprises an alkaline metal element or an alkaline-earth metal element,
• X comprises a halogen element,
• 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+, In+, Pb2+, Ag+, Cu+, Eu2+, Mn2+, 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
• wherein the light converting nanoparticle comprises an orthorhombic structure, a cubic structure, a rhombic dodecahedron structure, or a combination thereof.