8-hydroxyquinoline aluminum/nano-TiO2 composites were prepared via in situ. In order to make a better combination of the two component, Octavinyl-T8-silsesquioxane (8-vinyl POSS) was introduced into the composite system. The structure and properties of the samples were characterized by XRD, SEM, XPS, UV–visible absorption, Fluorescence spectra and Time-resolved emission-decay. These results show both β-phase and γ-phase of Alq3 exist in the composite products. Meanwhile, the addition of nano-TiO2 and 8-vinyl POSS does not change the crystalline and structure of as-prepared Alq3. Interestingly, however, XPS spectra shows that two new kinds of interaction forces emerge after the addition of 8-vinyl POSS, owing to the formation of Al–O–Si and Si–O–Ti bond, presumably. Besides, the emission intensity of Alq3/nano-TiO2 and Alq3/8-vinyl POSS/nano-TiO2 increases by 22% and 33%, respectively. The addition of TiO2 and 8-vinly POSS will not affect the position of emission peak, but will increase the transmission efficiency in electron–hole pairs. In the meantime, surprisingly, the modified Alq3 has a longer lifetime than as-prepared Alq3.

•Sr2CeO4: Eu3+, Dy3+ phosphors were synthesized by a polymer-network gel method.•The photoluminescence properties of Eu3+ and Dy3+ in Sr2CeO4 were investigated.•The PL mechanism cannot be explained only by the energy transfer model.•The defect conditions in crystals were also considered to clarify the PL mechanism.We report single-phased color-tunable phosphors (Sr2CeO4: Eu3+, Dy3+) synthesized by a polymer-network gel method for UV–LED. The photoluminescence properties and possible energy transfer mechanisms of Eu3+ and Dy3+ in Sr2CeO4 were investigated by experiments and first principles calculations. The results show that the 5D0 → 7F2 emission of Eu3+ is enhanced by the increase in the amount of Eu3+ ions and Eu3+ substitution makes more stable defect than Dy3+ substitution does. The photoluminescence mechanism of Sr1.994−xEuxDy0.006CeO4 can be explained by the energy transfer model with the consideration of the defect conditions in the crystals.Graphical abstract

A series of Eu0.5Tb0.5(TTA)3Phen/PMMA (TTA=thenoyltrifluoroacetone, Phen=phenanthroline) and Eu0.5Tb0.5(TTA)3Dipy/PMMA (Dipy=2,2′-dipyridyl) were prepared by in-situ polymerization. The structures of the composites were characterized by IR spectra and electron spectrum. Photoluminescence properties were investigated by UV-Vis spectra and fluorescence spectra. Meanwhile, the energy transfer models were set up. The results indicated that polymer parts were attached with the rare-earth molecular parts in the composite luminescent materials. Eu0.5Tb0.5(TTA)3Phen/PMMA and Eu0.5Tb0.5(TTA)3Dipy/PMMA emitted mostly characteristic fluorescence of europium ion and intense red fluorescence with peak wavelength at 611.8 nm and bandwidth of 10.4 nm under UV excitation at 365 nm. Fluorescence intensity of Eu0.5Tb0.5(TTA)3Phen/PMMA was found to be influenced with the content of MMA. The fluorescence emission of europium ions was greatly sensitized by terbium ions and the enhancement of red emission was most likely due to the energy transfer enhancement from Tb3+ to Eu3+.