Color-tunable silica-coated-carbon dot-encapsulated LaCaAl3O7:Eu3+ phosphor: Bridging advanced lighting and multimodal security applications

• A novel series of SiO 2 -coated CDs grafted onto LCAO:Eu 3+ phosphors was synthesized via solution combustion method using coconut water as fuel. • Incorporation of CDs into LCAO:Eu 3+ achieved a 21.32-fold increase in PL intensity, further amplified to an 88.69-fold increase with a SiO 2 coating, and attained a PL quantum yield of 87.72 %. • The CDs@LCAO:3Eu 3+ NCs exhibited tunable emission spectra from pink to deep blue, controlled by CDs' concentration. • The hybrid SiO 2 /CDs@LCAO:3Eu 3+ demonstrating sensitivity of 3.02 % K -1 at 460 K. While, fabricated wLED using SiO 2 /CDs(5 wt %)@LCAO:3Eu 3+ NCs achieved a CRI of 93. • SiO 2 /CDs@LCAO:3Eu 3+ NCs enabled the creation of unique multi-luminescent patterns offering robust solutions for secure product authentication. A novel series of silica (SiO₂) coated carbon dots (CDs) grafted onto LaCaAl₃O₇:Eu³⁺ (LCAO:Eu³⁺) hybrid phosphors is synthesized using a simple solution combustion method with coconut water as the fuel. These nanocomposites (NCs) are designed to enhance the photoluminescence (PL) properties of the LCAO:Eu³⁺ matrix. CDs improved the absorption cross-section of red-emitting Eu³⁺ ions, significantly increasing luminescence intensity. The NCs exhibited color tunability and temperature sensitivity, making them suitable for applications in lighting and anticounterfeiting. The NCs are synthesized by incorporating various concentrations of CDs into the LCAO:Eu³⁺ matrix, followed by SiO₂ coating to improve PL performance. The emission spectra are tuned by adjusting the CDs concentration and excitation wavelength. Comprehensive PL characterizations are performed, focusing on quantum yield (QY), luminescence intensity, and color tunability for practical applications. Incorporating CDs achieved a PL QY of 87.72 % and enhanced LCAO:3Eu³⁺ luminescence intensity 21.32-fold, further improved to 88.69-fold with SiO₂ coating. The NCs displayed tunable emission spectra (pink to deep blue) and a high CRI of 93 for white light emitting (w-LEDs). They functioned as optical thermometers with 3.02 % K⁻¹ sensitivity at 460 K. SiO₂/CDs(1, 3, 15, 25 wt %)@LCAO:3Eu³⁺ produced unique luminescent patterns, enabling robust anticounterfeiting and multi-level encryption for authentication.