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In2S3 layers were deposited by flash evaporation technique with varying flash rates. The optical constants of layers based on Tauc-Lorentz model dielectric function were extracted from spectroscopic ellipsometry measurements. X-ray photoelectron spectroscopic investigation revealed the presence of oxygen impurity in as-deposited and air-annealed layers with traces of Na inclusion in the layer grown at high flash rate. The enhancement in crystalline arrangement of as-deposited layer after air annealing was confirmed by Raman spectroscopy. Rutherford backscattering measurements revealed the growth of off-stoichiometric layers at all flash rates. An analytical layer growth model has been proposed supporting the results obtained by various layer characterization techniques. The solar cells were prepared with flash evaporated In2S3 buffer layers and their performances were compared with CdS reference solar cell. A significant gain in short-circuit current was obtained after air annealing of the complete device at 200 °C for 20 min. A maximum conversion efficiency of 12.6% was delivered by a high flash rate In2S3 buffered cell with open-circuit voltage close to that of CdS reference cell. The improvement in device performance after air annealing treatment is explained by thermally enhanced Cu and oxygen diffusion from Cu(In,Ga)Se2 and i-ZnO to In2S3 layer, respectively. [ABSTRACT FROM AUTHOR]

C60 have been used as an important active layer in organic solar cells and require elaborate understanding of its thin film properties. In this work, we present detailed morphological and ellipsometric studies on C60 thin films for understanding its growth and optical characteristics. At the initial stages of growth, C60 was found to form nanocrystalline granular domains in three-dimensional growth mode that coalesce to form large islandlike structures. As the film grows, comparatively smooth surfaces are obtained by uniform distribution of the nanocrystalline domains. Ellipsometric studies required the use of a bilayer structural model. The applicability of crucial model dielectric functions including Classical-Oscillator model, Forouhi–Bloomer model, and Tauc–Lorentz model for extraction of optical constants [Ñ(E)=n(E)+ik(E)] was investigated. The optical constants extracted from the three models are reported. Tauc–Lorentz model was found to be suitable model dielectric function as compared to the other models. Parameters including transition energy, amplitude, and broadening corresponding to five optical transitions, as well as the optical band gap of C60, are extracted. The optical constants are further used to model growth of the C60 film by studying evolution of the film and the roughness layers in the ellipsometric bilayer model. [ABSTRACT FROM AUTHOR]

[In.sub.2][S.sub.3] layers are deposited by flash evaporation method with varying flash rates and the optical constants of layers based on Tauc-Lorentz model dielectric function are extracted from spectroscopic ellipsometric measurements. The device performance improvement after air annealing treatment is described by thermally enhanced Cu and oxygen diffusion from Cu(In,Ge)[Se.sub.2] and I-ZnO to [In.sub.2][S.sub.3] layer.

Morphological and ellipsometric studies are used for understanding the growth and optical characteristics of [C.sub.60] thin films. The optical constants are used for modeling growth of the [C.sub.60] film by analyzing evolution of the film and the roughness layers in the ellipsometric bilayer model.