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

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 degrees 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.

Automated summary

The UV-induced photoluminescence of organosilica films with specific chemical groups was studied to understand the nature and origin of optically active defects. It was found that the sources of luminescence were carbon-containing components and carbon residues formed during the sample preparation process. A good correlation between the photoluminescence peaks and chemical composition was observed. The intensity of photoluminescence increased with porosity and internal surface area, and additional bands appeared after annealing, indicating changes in the matrix and segregation of residues on the surface.