N-doped SnO2 nanocrystals with green emission dependent upon mutual effects of nitrogen dopant and oxygen vacancy

A facile and economical chemical route was used to synthesize nitrogen-doped tin oxide (SnO2) nanocrystals (NCs). Infrared and Raman spectral examinations reveal the existence of oxygen vacancies and local disorder. Temperature-dependent photoluminescence (PL) measurements display a broad band at 640 nm at room temperature that shifts to a higher energy at lower measurement temperature. Excitation wavelength-dependent PL spectra show that the band blue-shifts and its line width decreases as the excitation wavelength is reduced. The PL peak also blue-shifts when the annealing temperature is increased. Spectral analysis and theoretical calculation suggest that the PL band stems from the mutual effects of oxygen vacancies and nitrogen dopants. This PL investigation on N-doped SnO2 NCs provides more insights about the optical properties and will promote further applications of SnO2 NCs.