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The thin film of Sb 2 Se 3 was deposited by thermal evaporation method and the film was annealed in N 2 flow in a three zone furnace at a temperature of 290• C for 30 min. The structural properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy, respectively. It is seen that the as-deposited film is amorphous and the annealed film is polycrystalline in nature. The surface of Sb 2 Se 3 film is oxidized with a thickness of 1.15 nm investigated by X-ray photolecetron spectroscopy (XPS) measurement. Spectroscopic ellipsometry (SE) and UV-vis spectroscopy measurements were carried out to study the optical properties of Sb 2 Se 3 film. In addition, the first principles calculations were applied to study the electronic and optical properties of Sb 2 Se 3 . From the theoretical calculation it is seen that Sb 2 Se 3 is intrinsically an indirect band gap semiconductor. Importantly, the experimental band gap is in good agreement with the theoretical band gap. Furthermore, the experimental values of n, k, ε 1 , and ε 2 are much closer to the theoretical results. However, the obtained large dielectric constants and refractive index values suggest that exciton binding energy in Sb 2 Se 3 should be relatively small and an antireflective coating is recommended to enhance the light absorption of Sb 2 Se 3 for thin film solar cells application.

Taken into account the curvature effects，we build a singleπ orbital tight-bi ndi ng model for armchair toroidal carbon nanotubes, from which the interaction matr i x elements have been derived by means of the wavefunction decomposition method. The electronic structures of armchair toroidal carbon nanotubes are studied, whi ch are dependent on both the torus radius and the tube radius. The energy spectr al transition is observed from the discrete to continuous ones, as the t orus radius and the tube radius are varied.

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