Synergistic Strategy of Homologous Lattice Doping and Phonon Engineering Enables Deep-Red Narrow-Band High-Efficiency Luminescence and Dynamic Anti-Counterfeiting Applications

To address the urgent demand for high-quantum-yield and low-thermal-quenching materials in WLED and dynamic anti-counterfeiting applications, this study innovatively proposes a homologous lattice doping coupled with phonon engineering strategy. By precisely substituting Y3+ sites in the garnet lattice with Gd3+, we overcome the luminescence limitations of conventional rare-earth materials, achieving the first controllable tunable 706nm far-red narrow-band emission. The optimized Ca3Y1.4Ge3O12: 0.6Eu3+ phosphor exhibits exceptionally strong 5D0→7F4 far-red transitions and disruptive optical performance: an internal quantum efficiency of 97%, external quantum efficiency of 38%, and absorption efficiency of 41%, significantly surpassing commercial Y2O3: Eu3+ and CaAlSiN3: Eu3+ benchmarks. Its thermal stability is remarkable, retaining 94.54% luminescence intensity at 150 °C (423K) and 90% at 210 °C, outperforming the thermal tolerance limits of KSF: Mn4+. Through groundbreaking phonon engineering theory, establishing a phonon-assisted lattice vibration model to decode electron-phonon coupling dynamics, revealing that the enlarged local phonon density at the Eu3+-centered oxygen octahedron accelerates energy exchange between excited electrons and phonons, fundamentally explaining its high absorption and quantum efficiencies. The fabricated WLED device demonstrates superior performance with correlated color temperature (4805K), color rendering index (93.5). Furthermore, three advanced applications of plant growth, screen printing anti-counterfeiting and information encryption are also explored, demonstrating excellent capabilities in anti-counterfeiting and information security. This work establishes a phonon-lattice-transition ternary engineering paradigm for high-stability deep-red luminescent materials and provides versatile solutions for next-generation optoelectronic systems.