High Refractive Index Silica-Titania Films Fabricated via the Sol-Gel Method and Dip-Coating Technique-Physical and Chemical Characterization

Chemical Doping of a Silica Matrix with a New Organic Dye from the Group of Heterocyclic Compounds—Chemical, Optical and Surface Characteristics

This paper presents the results of research on a luminescent dye bound in a silica matrix. The new developed dye from the group of azaheterocyclic compounds was used: 3-(p-hydroxyphenyl)-1-phenyl-1H-pyrazolo [3,4-b]quinoxaline. The structure and composition of the dye was examined by 1HNMR, 13CNMR, FTIR, and elemental analysis. Its absorption and photoluminescence characteristics were tested in solvents of different polarity in UV-Vis range. The films were prepared by sol–gel method and dip-coating technique. The dye was introduced into a sol in the course of a synthesis of the latter. DLS and FTIR measurements of sols were performed. Optical properties were investigated using UV-Vis spectrophotometry and monochromatic ellipsometry. The surface morphology of the layers was examined by atomic force microscopy. Our investigations showed that the dye bound in the silica matrix does not lose its photoluminescent properties. The emission band at λPL = 550 nm (λex = 365 nm) was recorded for the dye in the matrix. The layers are optically homogeneous with smooth surfaces. Dye doped silica films have RMS surface roughness of 2.17 nm over areas of 2 × 2 μm2. The idea of binding a photoluminescent dye in a silica matrix presented in the paper can be applied in the technology of luminescent solar concentrators.