1：Experimental Design and Method Selection:

The study involved the synthesis of Eu(TTA)3Phen (ETP) complex and its combination with fluorescein in a polyvinyl chloride (PVC) gold medium to prepare biluminescent security ink. The photophysical properties of the ink were analyzed using UV-vis absorption and PL excitation/emission spectra.

2：Sample Selection and Data Sources:

Europium (ΙΙΙ) oxide, 2-thenoyltrifluoroacetone, 1,10-phenanthroline, ethanol, sodium hydroxide, polyvinyl chloride gold medium, hydrochloric acid, and fluorescein were used for synthesizing/developing biluminescent security ink.

3：List of Experimental Equipment and Materials:

CHNS analyzer (Elementar Analysensysteme, Model: Vario Micro Cube), Avantes light source (Avalight-DH-S-BAL) and detector (Avaspec-2048), fluorolog-3 spectrofluorometer (FL3-11, Horiba Jobin Yvon), WITech alpha 300R+ confocal PL microscope system, 375 nm diode laser (wave-375-s-3v2-01001, Toptica), JSGW UV light source emitting at 367 nm, CCD detector (Avaspec-2048).

4：8). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: ETP was synthesized by dissolving europium oxide in dilute hydrochloric acid to prepare europium chloride, then mixing with 2-thenoyltrifluoroacetone, 1,10 Phenanthroline, and sodium hydroxide in ethanol. Biluminescent security ink was prepared by mixing fluorescein and ETP in PVC gold medium. The ink was used for screen-printing on various substrates.

5：Data Analysis Methods:

The PL excitation/emission spectra were recorded to analyze the luminescent properties of the ink. PL mapping was performed to examine the distribution of the fluorophore.