Size-dependent ultraviolet luminescence and low-field electron emission of TiO₂nanodots formed by phase-separation-induced self-assembly

We present a study of phase-separation-induced self-assembled TiO 2 nanodots. The Marangoni effect is utilized in the preparation of this TiO 2 nanostructure. Unique and strong ultraviolet (UV) luminescence is observed from the TiO 2 nanodots at room temperature. As the nanodot size reduces from 93 to 48 nm, the bandgap energy shifts from 3.43 to 3.76 eV and the luminescence peak energy increases from 3.38 to 3.58 eV. High electron emission at low electric field is also obtained from TiO 2 nanodots. The turn-on field and threshold field for emission current densities of 1 µA cm −2 and 1 mA cm −2 are as low as 0.7 and 3.7 V µm −1 , the lowest values ever reported for TiO 2 materials.