Tunable photoluminescence in sol-gel derived silica xerogels

摘要

Silica xerogels prepared by sol-gel method show blue emission under UV excitation with a smaller Stokes shift. The luminescent properties have been investigated under various preparation conditions and compositions. The silica xerogels show similar luminescent properties when using C_2H_5OH and N,N-dimethylformamide (DMF) as solvents, which are very different from those when using dimethylsulfoxide (DMSO) as solvent, i.e., a red shift of excitation and emission has been observed in the latter case. The emission intensity of the silica xerogels also depends on the water content and pH of the starting reaction solution. The introduction of organic group (-CH_3) in the silica xerogel modifies the network structure and further changes their luminescence properties. Heat treatment results in the decomposition of the organic (-SiCH_3) groups, which eliminates the old luminescent centers and produces new luminescent centers in longer wavelength simultaneously