Enhancement of Photostability Ageing of Samarium Complexes in PMMA Films

Several ligands have been selected to synthesize novel samarium complexes known for possessing good PLQY and excellent photostability ageing under weather and humidity conditions. New routes are open to design samarium complexes with high potential end-use for sustainable optoelectronic devices.

Abstract

In this study, a set of β-diketonate samarium(III) complexes–namely, [Sm(TTA)₃Phen], [Sm(TTA)₃DPEPO], [Sm(TTA)₃Bipy], and [Sm(TTA)₃Pyra]–has been synthesized and comprehensively characterized. Upon excitation, these complexes exhibit distinct emissions at 566 nm, 610 nm, 650 nm, and 710 nm, respectively, corresponding to the electronic transitions ⁴G_5/2→⁶H_5/2, ⁴G_5/2→⁶H_7/2, ⁴G_5/2→⁶H_9/2, and ⁴G_5/2→⁶H_11/2. Notably, the most pronounced pinkish-red emission is associated with the peak at 650 nm. Furthermore, the [Sm(TTA)₃DPEPO] complex displays a remarkable photoluminescence quantum yield, reaching up to 15.77 % in a PMMA film matrix. The investigation also involved a prolonged examination lasting over 1200 hours, during which PMMA films doped with the samarium complexes were subjected to humidity and weather conditions to evaluate their photoluminescence stability. The results indicate consistent emissions throughout the humidity test, with an eventual cessation after 1200 hours–except in the case of [Sm(TTA)₃Phen] under weather conditions. The enduring emission in this scenario is attributed to the robustness of the phenanthroline ligand, thus highlighting its role in enhancing the durability of the complex.

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