Spectroscopic investigation of spinel-type Mg2+aluminate activated with Eu3+ or Tb3+ and co-doped with alkali metals supported or not on PMMA film in the construction of PC-WLED prototypes

Abstract

Among the different architectures for the manufacture of WLEDs (white-light-emitting diodes), currently the already commercial Hybrid-LEDs based on the InGaN semiconductor and on the YAG:Ce phosphor, generate bluish white light, being still a challenge to produce them with lower temperature correlated color and higher color rendering index. The insertion of a red-emitting component would be an alternative, or the use of PC-LED (Phosphor-Converted LED) architectures, which combine red, blue, and green emitters in the coating of UV LEDs as an excitation source, generating white light. This BEPE proposal, linked to the Master's Project (Proc. FAPESP n. 2022/09504-0) in progress, aims to manufacture and investigate prototypes of monochromatic or white PC-LEDs using luminescent films of phosphors supported on PMMA as emitting components. MgAl2O4:Ln3+ (Ln3+ = Eu3+ or Tb3+) co-doped with alkali metals (Li+ , Na+ or K+) previously synthesized via the modified Pechini method, using sorbitol as a polymerizing agent, will be used in the manufacture of red-emitting films (Eu3+ as a dopant) or green (doped with Tb3+). For PC-WLEDs production, commercial blue emitter and prepared green and red emitters will be combined. This proposal seeks to deepen the investigation from the optical point of view of the produced systems, evaluating the influence of the insertion of co-dopants in the synthesized phosphors and its implications in the performance of the PC-LED prototypes. To this end, in addition to the conventional structural, spectroscopic, and morphological characterizations, high-resolution spectroscopy measurements of the materials will be carried out before and after they are supported on polymeric films, as well as to evaluate the performance of PC-LEDs prototypes based on luminous flux measurements, luminous efficacy and absolute quantum yield using integration sphere. Other essential figures of merit for the characterization of white LED prototypes will also be estimated, such as correlated color temperature and color rendering index. (AU)