2024

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Energy transfer characteristics in Tb(III)‒2,5-dihydroxybenzoic acid complex
(Elsevier Ltd, 2024) Pradeep Kumar Vishwakarma; S.B. Rai; A. Bahadur
Energy transfer through organic sensitization to ligand-centred Ln3+ ions is crucial for developing multifunctional materials with high brightness and good quantum yield from an application perspective. Gentisic acid (2, 5-Dihydroxybenzoic acid), as organic biomolecule is well known as the side minor metabolite of Salicylic acid/Aspirin and often used for palliative treatment. As fluorescence probes, significant optical absorption of 2, 5-DHBA in deep UV region fluoresce in near visible region and have also been employed to sensitize REs ions through metal-organic complexation. The present work emphasizes on the fluorescence assessment of DHBA, DHBA:Tb3+, PHEN:Tb3+, and DHBA/PHEN:Tb3+ complexes in PVA matrix as well as in aliphatic solvents. UV irradiation of DHBA embedded in PVA matrix or alcoholic solvent results in a vivid green emission of Tb3+ via linker-to-metal energy transfer (5D4→7F0-6). Moreover, the addition of PHEN pairing with DHBA:Tb3+ doped PVA matrix culminated in a broadened stimulus region (deep UV harvesting) and proficient energy transfer. Quantum Yield assessment revealed about the efficacy of DHBA is approximately 59 %, whereas for the optimized DHBA:Tb3+ in PVA matrix is about the 22 %. Colour tunability with Tb3+ concentrations, as well as the consequence of PHEN's as extended energy harvesting possibility, make it suitable for potential applications in optoelectronic devices, green LEDs, security inks, and biomarkers, etc. © 2024 Elsevier B.V.
Engineered ultra-luminous La/YPO4:Eu3+ nanophosphors for advanced security ink and latent fingerprint (LFPs) detection
(Elsevier Ltd, 2024) Prince Kumar; P.K. Vishwakarma; S.B. Rai; A. Bahadur
Designing versatile NPs for multifarious applications is crucial for achieving an array of criterion in realm, including improving efficiency, inexpensiveness, flexibility, least power consumption, etc. Facile hydrothermal treatment of La/YPO4:Eu3+ NPs yields composite phase growth signifying even-sized NPs with the requisite elemental composition. Relative CTB predominates in LaPO4:Eu3+; while luminescence of YPO4:Eu3+ is notably higher when stimulated by atomic lines. Nevertheless, La/YPO4:Eu3+ NPs exhibit adequate luminescence under both CTB and 394 nm (7F0→5L6) excitations, evincing intrinsic QY (63.91 %) with relatively large lifetime (∼6 ms) of 5D0 states, substantiated by J-O analysis. Designed NPs is readily cling to friction ridge skin residues demonstrating the efficient LFPs development through the ‘powder dusting approach’ on various substrate. NPs conjugated PVC gold medium and aqueous PVA were effectively used for security encryptions using the screen-printing technique. Reddish-orange emission with different excitation probabilities resulting in high QY emphasizes them in a class of futuristic versatile materials with potential applications in security ink, LFP development, LEDs, and display devices. © 2024 Elsevier B.V.