High photoluminescence quantum yield of TiO 2 nanocrystals prepared using an alcohothermal method

Highly dispersible TiO 2 nanocrystals (∼6 nm) were prepared by an alcohothermal method. A strong and stable photoluminescence emission with a maximum at 450 nm was observed in the original TiO 2 nanocrystals colloid. Compared with the emission from quinine sulphate in 0.05 mol/L sulphuric acid, the emission quantum yield of TiO 2 nanocrystals was determined to be about 0.20, which was much higher than the values (0.002 and 0.001) reported in previous studies. The fluorescence micrograph of TiO 2 nanocrystals encapsulated in lipsomes shows that TiO 2 nanocrystals prepared in such a way have potential application as a fluorescence probe in biological imaging. Research on the luminescence mechanism indicates that the surface state and extent of crystallization of the TiO 2 nanocrystals are crucial factors in the high photoluminescence quantum yield obtained in this study. Copyright © 2007 John Wiley & Sons, Ltd.