Highly efficient Dy3+ activated Sr9Al6O18 nanophosphors for W-LEDs, optical thermometry and deep learning-based intelligent system for personal identification applications

• A series of single-phase Dy 3+ activated Sr 9 Al 6 O 18 nanophosphors are synthesized via solution combustion route using urea as fuel. • The photoluminescence spectra of phosphors excited at 350 nm show intense emissions at 484 nm and 574 nm, corresponding to the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions. • Internal quantum efficiency (I QE ) of 66.14 %, the optimized phosphor achieves remarkable relative sensitivity (S r ) and absolute sensitivity (S a ) are estimated to be 2.65 % K −1 and 1.38×10 -3 K −1 at 300 K. • Latent fingerprints and latent lip prints can be efficiently produced on a variety of surfaces by using the optimized nanophosphors via simple powder dusting method. • The YoLOv8x approach analyses the overall morphological correlations of different minutiae to identify essential minutiae that indicate the identities of people from FPs. A novel single-phase Dy 3+ activated Sr 9 Al 6 O 18 nanophosphors (NPs) was synthesized using a solution combustion method with urea as the fuel. When phosphors are excited at 350 nm, their photoluminescence (PL) spectra exhibit strong emissions at 484 and 574 nm, which are associated with the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions. These emissions are attributed to magnetic and electric dipole allowed transitions, correspondingly. It is found that dipole–dipole interactions are the main source of concentration quenching and energy transfer among the activator ions. The prepared NPs show thermal stability up to 480 K having an activation energy (E a ) of 0.2437 eV, as determined by temperature-dependent photoluminescence (TDPL). With a remarkable internal quantum efficiency (I QE ) of 66.14 %, the optimized phosphor achieves notable relative sensitivity (S r ) and absolute sensitivity (S a ), estimated to be 2.65 % K −1 and 1.38×10 −3 K −1 at 300 K, respectively. Thus, Sr 9 Al 6 O 18 :Dy 3+ is a promising material for non-contact optical thermometry applications. Latent fingerprints (LFPs) and latent lip prints (LLPs) can be efficiently produced on a variety of surfaces by using the optimized NPs with the simple powder dusting technique. The prints are made visible under UV light with a 365 nm wavelength. The You Only Look Once version 8 ( YOLOv8x ) approach analyzes the overall morphological correlations of different minutiae to identify essential minutiae that indicate the identities of people from FPs. Splitting and matching multi-scale fingerprints (FPs) features improves the validity of the authenticating findings. The results show that the recommended method, which improves the entire FP authentication process, offers exceptional accuracy, resilience and speed. The findings provide strong support for the implementation of the optimized NPs in photonic devices, optical thermometers, and advanced forensic applications.