Structure-Dependent Photoluminescence of Europium(III) Coordination Oligomeric Silsesquioxane: Synthesis and Mechanism

Abstract

The coordination environment of Eu3+ is a crucial factor in the optical performance of the complex. Herein, a new kind of oligomeric silsesquioxane was employed to improve the coordination environment of central ions, the luminescence intensity of which was greatly enhanced with an efficient emission peak at 619 nm. More importantly, the photoluminescent properties of the product will be altered because of the formation of the Si–O–Si structure. The relevant mechanism has also been investigated and proposed by a series of characterization analyses. Additionally, the fluorescence lifetime, intrinsic quantum yield, and energy transfer efficiency were calculated. In addition, the observed trend of Judd–Ofelt intensity parameters was used to justify the coordination environment of Eu3+ ions. The experimental results reveal that the sol–gel reaction of the ligands can effectively promote intramolecular energy transfer. In addition, we introduced four theory modules of ligands (LSi, LSi-1, LSi-2, and LSi-3) with certain rules of formation of Si–O–Si, and density functional theory (DFT) and time-dependent DFT (TD-DFT) were used to explore their excited electron transfer process and their electronic absorption spectra, combined with Marcus theory. The calculated results show that the sol–gel reaction will induce the separation of the distribution of excited holes and electrons, leading to an efficient charge-transfer (CT) process. The predictable results were in good accordance with the experimental findings. Consequently, the sol–gel reaction occurring among ligands will be attributed to an efficient CT process, leading to a strong luminescence intensity, as observed experimentally.

Ethyl Cellulose/Rare Earth Complexes Light‐Conversion Films and Exploration in Acid Rain Detection

“…Like the C spectrum, the binding energy of C═O has also decreased(−0.023 eV), but the binding energy of C-O has increased(0.006 eV). [38] The results showed that H + could catalyze the ligand, and the coordination mode of BTA with rare earth ions changed from the original chelating bidentate coordination to monodentate coordination mode, which reduced the energy transfer efficiency between the ligand and rare earth ions. [39]…”

Exploring the potential of Eu3+ and Mn4+ activated LaAlO3 phosphors as red and far-red emitters for horticulture lighting

“… 4 One of the RE 3+ ions that consists of partially filled f-orbitals and is highly efficient in the red region is Europium (Eu 3+ ). 5 On the other hand, TM ions are a group of elements characterized by their partially filled d-orbitals, or the ability to form such orbitals. One such TM ion is Manganese (Mn) in its 4+ state and is known for its efficient far-red emission.…”