Red-light-emitting inorganic La2CaZnO5 frameworks with high photoluminescence quantum efficiency: Theoretical approach

Abstract A series of Eu 3 + doped CaLa 2 ZnO 5 (CLZ) phosphors varying the Eu 3 + concentration have been synthesized by the combustion route. The crystal structure, luminescent properties, thermal stability, quantum efficiency and the use of the phosphor in the phosphor-converted light emitting diodes (LEDs) were investigated in detail. The X-ray diffraction results confirmed the formation of a single-phase CLZ with a tetragonal symmetry. The crystal structure was refined via the Rietveld method, and it was observed that the crystal structure was composed of three different interlinked polyhedra LaO 8 , CaO 10 and ZnO 4 , which makes the structure very stable. The CLZ:Eu 3 + phosphors irradiated with ultraviolet and blue light exhibited the characteristic red photoluminescence (PL) emissions owing to the 5 D 0  →  7 F J transitions. The optimized CLZ:5% Eu 3 + phosphor showed an excellent thermal stability of 90% up to 498 K. The internal quantum efficiency of the optimized CLZ:5% Eu 3 + was found to be 55.48% under the blue excitation of 467 nm. The excellent color purity of 91%, luminescence efficiency and stability with CIE coordinates at the pure red end (x = 0.64, y = 0.34) makes CLZ:Eu 3 + phosphor an efficient red emitting candidate for UV and blue LED chips.