Amalgamation of composite flux as luminescent armor in Eu3+ doped BaLa2ZnO5 phosphor for enhanced luminescence, combating counterfeiting, improving thermal sensing and advanced forensic investigations

The synthesis of BaLa2ZnO5:Eu3+ phosphors with single and composite fluxes is carried out using the solution combustion route. An extensive investigation is undertaken to evaluate how these fluxes affect the morphology, crystallization and luminescence characteristics of the BaLa2ZnO5:Eu3+ phosphor. The results unveiled a notable influence of the composite fluxes on the luminous characteristics of the phosphor. Specifically, the addition of composite fluxes led to notable enhancements in the emission intensity of the phosphor, with increases of similar to 1.2, 1.36, 2.30 and 2.62 folds observed for NH4Cl, Na2CO3, NH4HF2 and H3BO3, respectively. On the other hand, the addition of composite fluxes resulted in even greater enhancements, with increases of approximately 2.9, 3.5 and 5.1 folds observed for H3BO3 + NH4Cl, H3BO3 + Na2CO3, and H3BO3 + NH4HF2 composite fluxes. Moreover, the optimized H3BO3 + NH4HF2 added composite phosphor exhibited high colour purity (CP: 98.77 %) and internal quantum efficiency (I-QY: 86.26 %). Phosphorus is exposed to temperatures as high as 498 K in order to assess its thermal stability, revealing that the optimized composite phosphor exhibited enhanced thermal stability, characterized by an activation energy (E-a) of 0.31 eV. The distinct characteristics of this luminescent material suggest its potential application in manufacturing white-light-emitting devices for solid-state lighting. An optimized composite H3BO3 + NH4HF2/BLZO:7Eu(3+) is utilized for latent fingerprints (LFPs) development on diverse substrates via a simple powder dusting (PD) method. Subsequently, we devised a deep learning model for fingerprints (FPs) recognition using the YOLOv8x algorithm, which is subsequently employed for FP analysis. The optimized H3BO3 + NH4HF2/BLZO:7Eu(3+) composite is utilized for various forensic applications, including LFPs and security ink. The LFPs stained with the composite exhibited clear images with discernible level I-III characteristics. Furthermore, we used the optimised phosphor to create anti-counterfeiting (AC) security ink, which we used to encrypt data on a variety of surfaces. Overall, the results clearly show that the composite phosphor is suitable for AC applications, LFP visualization, and solid-state illumination.