Highly stable colloidal TiO2 nanocrystals with strong violet-blue emission

Improved sol-gel method has been applied to prepare highly stable colloidal TiO2 nanocrystals. The synthesized titania nanocrystals exhibit strong emission in the violet-blue wavelength region. Very long evolution time was obtained by preventing the sol to gel conversion with reflux process. FTIR, XRD, UV-vis absorption, photoluminescence and high resolution transmission electron microscope (HRTEM) were used to study the optical properties, crystalline phase, morphology, shape and size of prepared TiO2 colloidal nanocrystals. HRTEM showed that the diameter of TiO2 colloidal nanocrystals is about 5 nm. Although the PL spectra show similar spectral features upon excitation wavelengths at 280, 300 and 350 nm, but their emission intensities are significantly different from each other. Photoluminescence quantum yield for TiO2 colloidal nanocrystals is estimated to be 49% with 280 nm excitation wavelength which is in agreement and better than reported before. Obtained results confirm that the prepared colloidal TiO2 sample has enough potential for optoelectronics applications.