Exploration of Optical and Radiative Properties of Fluorinated β-keto Carboxylate Tb3+ Complexes Emanating Cool Green Light

Tb 3+ complexes with β-ketocarboxylic acid as main ligand and heterocyclic systems as auxiliary ligand were synthesized and analyzed to assess their prospective relevance as green light emitting material. The complexes were characterized via various spectroscopic techniques and were found to be stable up to ≈ 200 ℃. Photoluminescent (PL) investigation was performed to assess the emissive nature of complexes. Longest luminescence time of decay (1.34 ms) and highest intrinsic quantum efficiency (63.05%) were fetched for complex T5. Color purity of complexes was found to be in range 97.1 – 99.8% which demonstrated the aptness of these complexes in green color display devices. NIR Absorption spectra were employed to evaluate Judd–Ofelt parameters to appraise the luminous performance and environment encircling Tb 3+ ions. The JO parameters were found to follow the order: Ω 2 > Ω 4 > Ω 6 and suggested the higher covalence character in complexes. Theoretical branching ratio in the range 65.32 – 72.68%, large stimulated emission cross section and narrow FWHM for 5 D 4 → 7 F 5 transition unlocked the relevance of these complexes as a green color laser media. Band gap and Urbach analysis were consummated via enforcing nonlinear curve fit function on absorption data. Two band gaps with values in between 2.02 – 2.93 eV established the prospective use of complexes in photovoltaic devices. Energies of HOMO and LUMO were estimated employing geometrically optimized structures of complexes. Investigation of biological properties accomplished via antioxidant and antimicrobial assays which communicated their applicability in biomedical domain.