Abstract
SnO2 and F doped SnO2 (FTO) nanoparticles (NPs) have been synthesized by the hydrothermal method with subsequent annealing at 500 °C. The microstructure and photoluminescence (PL) property of SnO2 and FTO NPs have been investigated, and an assumption model about the luminescence process of FTO NPs has been proposed. All of the SnO2 and FTO NPs possess polycrystalline tetragonal rutile structures, and the average size in the range of 16.5–20.2 nm decreases with the increasing of F doping content. The doping element F is shown a uniformly distribution by electron energy loss spectroscopy (EELS) mapping. The oxygen vacancy concentration becomes higher as is verified by Raman and X-ray photoelectron spectra (XPS). There are three kinds of oxygen chemical states in SnO2 and FTO NPs, in which Oα corresponds to oxygen vacancies. The room temperature PL position is observed to be independent of F doping content. F− may substitute O2− into the SnO2 lattice by generating and one extra e−, which can combine with or to generate or to ensure charge balance.
Highlights
Great interest has been attracted in the photoluminescence (PL) properties of many wide direct band gap semiconductors, due to their promising applications in short-wavelength optical devices, such as fluorescent lamps, plasma display panels (PDPs), light emitting diodes (LEDs), laser diodes (LDs), and so on [1,2,3,4]
Ahmed et al [15] pointed that the enhancement of the visible emission of Ni doped SnO2 nanoparticles could be attributed to the oxygen vacancies that are created by the substitution of Sn4+ by Ni2+
Images, as well as electron energy loss spectroscopy (EELS) mapping were performed by transmission electron microscopy (TEM, JEM-2010 spectrometer, JEOL, Tokyo, Japan)
Summary
Great interest has been attracted in the photoluminescence (PL) properties of many wide direct band gap semiconductors, due to their promising applications in short-wavelength optical devices, such as fluorescent lamps, plasma display panels (PDPs), light emitting diodes (LEDs), laser diodes (LDs), and so on [1,2,3,4]. Ahmed et al [15] pointed that the enhancement of the visible emission of Ni doped SnO2 nanoparticles could be attributed to the oxygen vacancies that are created by the substitution of Sn4+ by Ni2+. Electronegativity of F− (χ F− ≈ 4.368) is more pronounced than O2− (χO2− ≈ 3.758) It is much easier for F− to replace O2− in the SnO2 lattice and generate oxygen vacancies [18,19,20,21,22,23,24]. Shewale et al [6] obtained an intense violet emission at 404 nm with a shoulder peak at 396 nm of F doped SnO2 (FTO) films deposited by advanced spray pyrolysis technique at low substrate temperature. The mechanism and the position of defect energy level in the band gap are discussed in detail, and an assumption model about the PL process of FTO NPs will be proposed
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