Spectrally Programmable Ag₂WO₄ Nanophases: Defect-Orchestrated Emission Reconfiguration for High-Fidelity Photonic...

Orthorhombic-phase silver tungstate (Ag₂WO₄), a polymorphic ternary oxide, was synthesized through hydrothermal methods and thoroughly examined for its crystallographic accuracy, quantum optical behavior, and photonic applications. The gradual adjustment of synthesis time led to morphological phase changes from disordered anisotropic rods to well-defined polyhedral grains, as confirmed by XRD and FESEM. The elemental composition and stoichiometry were validated using EDX and hyperspectral color mapping, which demonstrated atomic-level uniformity. UV-Vis. spectroscopy revealed significant ligand-to-metal charge transfer (LMCT) transitions (O 2p → W 5d/Ag 4d), enhanced by defect-induced intra-bandgap states and localized surface plasmon resonances (LSPR), resulting in a tunable optical bandgap (1.38-2.89 eV). Urbach tail analysis illustrated disorder-induced band edge smearing and electronic localization. Time-resolved and steady-state photoluminescence studies showed biexponential and trap-assisted recombination kinetics, with W1 achieving the highest quantum yield (Φ = 0.693) and ultrafast lifetime decay (τ = 2.1 ns), indicating low non-radiative losses. CIE, NCS, and TM-30-18 vector analyses provided insights into precise chromaticity engineering, revealing high spectral fidelity (R_f = 86.4), an optimized color gamut (R_g = 98), and perceptual hue shifts across the emission spectrum. SPD and ΔE_ab assessments demonstrated spectral coherence, minimal chromatic aberration, and excellent color rendering. Notably, the material's defect-tunable, dye-free photoluminescence facilitated multispectral latent fingerprint detection with sub-micron resolution, linking quantum materials science with forensic biophotonics. These results establish Ag₂WO₄ as a promising plasmonic-semiconducting hybrid for cutting-edge optoelectronic systems, biometric sensing, and high-index photonic coatings.