Li+ co-doping enabled lattice engineering and high-performance luminescence in BaYAlZn3O7:Eu3+ phosphors for optoelectronic and forensic applications

This study presents solution combustion synthesis and comprehensive investigation of Eu 3+ activated BaYAlZn 3 O 7 (BYAZ:Eu 3+ ) phosphors, emphasizing the remarkable enhancement in photoluminescent (PL) performance achieved through Li + co-doping. The incorporation of Li + ions effectively compensate for the lattice distortion caused by Eu 3+ substitution at Y 3+ sites, leading to improved crystallinity. The optimized BYAZ:5%Eu 3+ ,3%Li + composition exhibits an 11.23 folds enhancement in emission intensity, producing bright orange-red luminescence with a color purity (CP) of 92.09 %, a correlated color temperature (CCT) of 2284 K, and an internal quantum efficiency (I QE ) of 89.28 %. The BYAZ:5%Eu 3+ ,3%Li + phosphor maintains excellent luminescence stability across 300–510 K, retaining 91.01% of its intensity at 420 K compared to room temperature (300 K) and exhibited a relative sensitivity (Sᵣ) of 3.01% K -1 . Furthermore, the flexible PVA/BYAZ:5%Eu 3+ ,3%Li + films show excellent mechanical durability, thermal stability, and water resistance, and their luminescence remains stable even when the polymer matrix is deformed, indicating that the optical performance of the embedded phosphor is not affected by such mechanical stresses. The BYAZ:5%Eu 3+ ,3%Li + phosphor demonstrates fingerprint visualization capabilities, particularly in resolving Level I–III ridge details on diverse substrates. Overall results confirms that Li + incorporation in BYAZ:5%Eu 3+ significantly improves luminescence, stability, making it a promising material for optical devices and forensic applications. 1. Eu 3+ doped and Li + co-doped BYAZ:Eu 3+ phosphor synthesised via solution combustion method. 2. Li + co-doping in BYAZ:Eu 3+ achieves 11.23-fold photoluminescence enhancement with I QE of 89.28%. 3. Optimized BYAZ:5%Eu 3+ ,3%Li + phosphor retains 90.01 % emission intensity at 420 K, exhibit S r of 3.01% K -1 . 4. PVA/BYAZ:5%Eu 3+ ,3%Li + films exhibit excellent flexibility and stability, making them suitable for optoelectronic applications.