Micro-mesoporous submicron silica particles with pore size tunable in a wide range: synthesis, properties and prospects for LED manufacturing.

An approach has been developed that allows the synthesis of submicron spherical silica particles with a controlled micro-mesoporous structure possessing a large specific surface area (up to 1300 m2g-1). Particle synthesis is carried out by hydrolysis of a mixture of various organosilanes mostly associated either with CTAB or with each other. A change in the concentration of CTAB in the reaction mixture apparently leads to a change in the formation mechanism of nuclei for the silica particles growth, which allows varying the diameter of the synthesized particles in the range from 40 to 450 nm. The effect of the composition of silica precursor ([3-(methacryloyloxy)propyl]trimethoxysilane, (3-aminopropyl)triethoxysilane and tetraethoxysilane) on the formation process and the porosity of the resulting particles is studied. It was shown that simply varying the ratio of organosilanes in the composition of the precursor, one can control the pore diameter of the particles in the wide range from 0.6 to 15 nm. The large-pore (up to 15 nm) silica particles are used as a matrix for spatial distribution of luminescent carbon dots. Incorporation of carbon dots into SiO2particles prevents their aggregation leading to emission quenching after drying, thus allowing to obtain highly luminescent composite particles. LEDs based on obtained composite material show bright visible luminescence with spectral characteristics similar to that of a commercial cold white LED.