UV-Excited Luminescence in Porous Organosilica Films with Various Organic Components

Abstract

UV-induced photoluminescence of organosilica films with ethylene and benzene bridging groups in their matrix and terminal methyl groups on the pore wall surface was studied to reveal optically active defects and understand their origin and nature. The careful selection of the film’s precursors and conditions of deposition and curing and analysis of chemical and structural properties led to the conclusion that luminescence sources are not associated with the presence of oxygen-deficient centers, as in the case of pure SiO2. It is shown that the sources of luminescence are the carbon-containing components that are part of the low-k-matrix, as well as the carbon residues formed upon removal of the template and UV-induced destruction of organosilica samples. A good correlation between the energy of the photoluminescence peaks and the chemical composition is observed. This correlation is confirmed by the results obtained by the Density Functional theory. The photoluminescence intensity increases with porosity and internal surface area. The spectra become more complicated after annealing at 400 °C, although Fourier transform infrared spectroscopy does not show these changes. The appearance of additional bands is associated with the compaction of the low-k matrix and the segregation of template residues on the surface of the pore wall.

Structural and Luminescence Properties of Eu-Doped PMO Films with Ethylene Bridge and Methyl Terminal Groups

“…Figure 11 demonstrates the dependence of the photoluminescence intensity on the wavelength of the excited light. The highest PL intensity is observed when the excitation wavelength is 230 nm, which aligns with previously reported data [34].…”

“…Figure 11 demonstrates the dependence of the photoluminescence intensity on the wavelength of the excited light. The highest PL intensity is observed when the excitation wavelength is 230 nm, which aligns with previously reported data [34]. Practical fluorescence quenching, caused by the aggregation of Eu 3+ , becomes evident in silica glass when the Eu content exceeds 1% (molar ratio) [45].…”

“…The photoluminescence spectra of 0 wt% Eu (pristine) and 12.1 wt% Eu-doped soft bake (SB) and hard bake (HB) nanoporous OSG films are shown in Figure 8. The pristine sample (fully cured) shows a single PL peak located near 300 nm (4.2 eV), which is related to the presence of a methyl terminal group and a carbon residue [34]. Thermal curing enhances the intensity of photoluminescence and broadens the emission spectra.…”

Recent Developments in Photoluminescent, Photothermal and Photocatalytic Nanomaterials

“…The photoluminescent materials investigated include crystalline tris(8-hydroxyquinoline) aluminum (Alq3) micro-rods (MRs), Fe 2+ -doped CsPb(Cl x Br 1−x ) 3 nanocrystals (NCs), organosilica films, and Tm 3+ -doped SiO 2 –HfO 2 [ 4 , 5 , 6 , 7 ]. Kim et al fabricated hybrid Alq3/Ag structures using a self-assembly method under a mixed solution of protic and aprotic polar solvents [ 4 ].…”

“…They showed that the PL intensity could be improved by increasing the porosity and internal surface area. Wu et al prepared Fe 2+ -doped CsPb(Cl x Br 1−x ) 3 NCs using a hot injection method [ 6 ]. Since the defect density was reduced by the Fe 2+ doping, the full width at half maximums declined, while PL quantum yields (QYs) and photostability increased.…”