Quasi-reversible photoluminescence quenching of stable dispersions of silicon nanoparticles

Optically clear and stable dispersions of brightly photoluminescent Si nanoparticles were obtained by covalent attachment of alkenoic compounds to the particles. Quenching of photoluminescence by ethylamine, diethylamine, triethylamine, pyrazine, and piperazine was investigated. The photoluminescence was quenched by the action of these nitrogenous species, but in some cases could be partially restored by the addition of trifluoroacetic acid. The extent of restoration of photoluminescence, after equilibrium is reached, was independent of the sequence of addition of the amine and the acid. The photoluminescence quenching and recovery are influenced by a combination of basicity, polarity, and steric factors of the quencher molecules. The quenching and subsequent restoration occurs gradually at room temperature and it takes several minutes to reach equilibrium.