Synthesis, crystal structure and photoluminescence properties of novel double perovskite La2CaSnO6:Eu3+ red-emitting phosphors

Abstract

A series of new double perovskite La2–xEuxCaSnO6 (0 ≤ x ≤ 0.8) red phosphors were synthesized by traditional solid-state reaction. The phase, microstructure, photoluminescence (PL) properties, quantum efficiency, and thermal stability of the phosphors were investigated. La2CaSnO6 matrix has a monoclinic double perovskite structure with space group P21/n. Under near-ultraviolet (UV) light at 395 nm, La2–xEuxCaSnO6 phosphors exhibit the most typical red emission peak at 614 nm, which corresponds to 5D0→7F2 electric dipole transition of Eu3+. The optimum Eu3+ doping content is attained at x = 0.5, and the La1.5Eu0.5CaSnO6 phosphor shows a moderate quantum efficiency (32.3%) and high color purity (92.2%). Besides, the temperature-dependent spectrum of the phosphor was studied. The emission intensity of Eu3+ at 423 K decreases to 70.94% of the initial intensity at 303 K, and the activation energy ΔE is estimated to be 0.232 eV, suggesting that the phosphors possess good thermal stability. The fabricated w-LED based on the phosphors has higher Ra (89), lower CCT (4539K), and better chromaticity coordinates (0.371, 0.428). These results prove that the Eu3+-doped La2CaSnO6 red phosphor has great potential applications in w-LEDs.