Luminescent composite materials

A composite material comprising a matrix and embedded therein luminescent crystals;

• said luminescent crystals being selected from compounds of formula (I)
• (M1A1)aM2bXc (I), wherein
• A1 represents one or more organic cations selected from the group consisting of ammonium, formamidinium, guanidinium, imidazolium, pyridinium, pyrrolidinium, protonated thiourea,
• M1 represents one or more alkaline metal cations selected from Cs, Rb, K, Na, Li,
• M2 represents one or more metal cations selected from the group consisting of Ge, Sn, Pb, Sb, Te and Bi,
• X represents one or more anions selected from the group consisting of chloride, bromide, iodide, cyanide, thiocyanate, isothiocyanate and sulfide,
• a represents 1-4,
• b represents 1-2,
• c represents 3-9;
• and
• said matrix being selected from compounds of formula (II)
• M3dX2e (II), wherein
• M3 represents one or more metal cations selected from Li, Na, K, Rb, Mg, Ca, Sr, Ba, Ti, Y, Zr, Zn, and Al,
• X2 represents one or more anions selected from the group consisting of halides, pseudo-halides, perchlorates, sulfates, sulfites, phosphates and phosphites,
• d represents 1 and e represents 1, 2 or 3, or
• d represents 2 and e represents 1 or 3, or
• d represents 3 and e represents 1 or 2,
• said composite material being present as a population of microparticles having a diameter in the range of 50-200,000 nm, and wherein the compounds of formula (I) are present in a concentration of more than 10 wt %.