Phosphors based spnellium of type AB2O4 (A = Mg2+, Ca2+, Sr2+; B = Al3+) doped with Eu3+ ou Tb3+ and co-doped with alkali metals for application in white light emitting diodes

Abstract

Among the different architectures for manufacturing WLEDs (white-light-emitting diodes), devices applied in solid-state lighting, the already commercial Hybrid-LEDs based on the semiconductor InGaN and the YAG:Ce phosphor, generate bluish white light. It is a challenge, therefore, to produce devices with lower correlated color temperature and higher color rendering index. To this end, inserting a component that emits in red would be an alternative, or the use of PC-LED architectures, which combine red, blue and green phosphors in the coating of UV LEDs as a source of excitation, generating white light emission. Thus, this proposal aims at the synthesis via modified Pechini method using sorbitol as a polymerizing agent of AB2O4:Ln(III) type phosphors (A = Mg2+, Ca2+ or Sr2+; B = Al3+; Ln(III) = Eu3+ or Tb3+ ) co-doped with alkali metal (Li+, Na+ or K+), in order to obtain red emitters, in the case of Eu3+, or green, when using Tb3+, for the production of monochromatic or white PC-LEDs. The optimal doping concentration and the use of alkali metals in co-doping will be investigated for charge compensation, avoiding the formation of unwanted defects, and seeking high luminous efficacy. For a better understanding and interpretation of the produced systems, and the influence of the co-dopant insertion, in addition to the characterization via structural, spectroscopic and morphological techniques, theoretical and semi-empirical studies of their structural, optical and electronic properties will be carried out. The most promising systems will be used in the manufacture of luminescent films from the insertion in a polymeric matrix of PMMA and PC-LED prototypes will be made and characterized.