Efficient Ce ³⁺ → Tb ³⁺ Energy Transfer in RbY ₃ F ₁₀ Phosphor for High-Contrast Latent Fingerprint Visualization

Ce 3+ /Tb 3+ codoped RbY 3 F 10 nanophosphors were synthesized by a microwave-assisted solvothermal method and investigated as UV-excited green-emitting materials for latent fingerprint visualization. The study combines structural characterization, steady-state and time-resolved photoluminescence spectroscopy, and proof-of-concept fingerprint development to clarify the relationship between Ce 3+ → Tb 3+ sensitization and practical imaging performance. Powder X-ray diffraction confirmed the formation of a single-phase face-centered cubic structure (Fm 3̅ m) and successful dopant incorporation, while TEM, EDS, and elemental mapping analyses revealed flower-like aggregates composed of ∼40 nm primary nanoparticles and a homogeneous distribution of Ce 3+ and Tb 3+ ions throughout the particles. Photoluminescence measurements revealed efficient sensitization of Tb 3+ green emission via Ce 3+ → Tb 3+ energy transfer under UV excitation. The composition showing the highest emission intensity within the investigated series was RbY 2.1 Ce 0.3 Tb 0.6 F 10 . The optimized phosphor exhibits a strong emission peak at 544 nm with an internal quantum yield of 0.47 under 258 nm excitation. Time-resolved photoluminescence measurements revealed a significant shortening of the Ce 3+ emission lifetime as Tb 3+ concentration increased (0–20 mol %), with a maximum energy transfer efficiency of ∼90% at the optimized composition. Analysis based on Dexter’s multipolar interaction model indicated a dipole–dipole dominated mechanism, supported by a critical transfer distance of ∼7.5 Å. The combination of high energy-transfer efficiency and stable green emission under UV excitation indicates that Rb-based fluoride hosts are suitable for Ce 3+ /Tb 3+ systems, and their possibility for latent fingerprint visualization was experimentally demonstrated.