The low cost, environmental harmless Cu
2ZnSnS
4 (CZTS)-based thin film solar cells are fabricated by using abundant materials. The CZTS film possesses promising characteristic optical properties; ...band-gap energy of about 1.5 eV and large absorption coefficient in the order of 10
4 cm
−
1
. All constituents of this CZTS film, which are abundant in the crust of the earth, are non-toxic. Therefore, if we can use CZTS film practically as the absorber of solar cells, we will be free from both of the resource saving problem and the environmental pollution.
In our CZTS project, CZTS absorber films were prepared by two independent techniques. One is three rf sources co-sputtering followed by annealing in sulfurized atmosphere. The latest conversion efficiency of over 6.7% was achieved by this technique. The other is co-evaporation technique. CZTS films were grown on Si (100) by vacuum co-evaporation using elemental Cu, Sn, S and binary ZnS as sources. XRD patterns indicated that the polycrystalline growth was suppressed and the orientational growth was relatively induced in a film grown at higher temperatures.
In this presentation, the development of CZTS-based thin film solar cells will be surveyed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In our previous study, we observed Hele-Shaw flows of two solutions of a polymer material around two cylinders and through two slits with different lengths. Based on the results, we showed that the ...potential flow analogy by the Hele-Shaw flow holds when the flow rate is very low in spite of the shear-thinning viscosity and elasticity of the fluids in steady shear flow. It was suggested that the potential flow pattern of the polymer solutions in the Hele-Shaw cell is disturbed by the effect of elongational stress. In this study, a simple method for planar elongational viscosity measurement is devised using the converging flow upstream the slit entry; the elongation rate is estimated from dye streak pattern in the inflow region formed upstream the slit entrance and the elongational stress is obtained from integrated equations of motion. The planar elongational rheometry presented in this work is advantageous due to its applicability to mobile fluids, in addition to its simple experimental set up.
The validity of potential flow analogy by the Hele-Shaw flow of non-Newtonian fluids is examined through experiments using two shear-thinning elastic polymer solutions for three different flow ...configurations, i.e. flows around a circular cylinder and a square cylinder and flows through an abruptly converging-diverging channel (slit). Although the polymer solutions are highly shear-thinning and elastic, their flows well reproduce the corresponding two-dimensional potential flow patterns of the respective flow configurations when the flow rate is very low. The deviation occurs at values of Reynolds number much lower than the critical value for inertia effect, and in the opposite way of the inertia effect. An analysis for inelastic non-Newtonian fluids shows that non-constant viscosity does not affect the potential flow analogy, and the potential flow patterns are observed at flows with considerable values of the first normal stress difference in shear flow. Therefore, the disturbance to the potential flow pattern is not due to the non-Newtonian viscosity or the elasticity in shear flow, but attributed to the elongational stress due to the elasticity of the polymer solutions.
In this study, the Hele-Shaw cell is used to examine the effect of fluid elasticity on the flow patters of two-dimensional flow. Flows around a circular cylinder, a square cylinder and flows through ...abruptly converging-diverging channels (slits) with different throat lengths are tested for water and 0.2 wt % polyacrylamide aqueous solution (PAA-solution). The viscosity of the latter is well modeled by the power law, and the first normal stress difference in the steady shear flow is arouind ten times higher than the shear stress. Although the two-dimensional potential flow patterns that correspond to the respective flow configurations when the flow rate is very low. The potential flow patterns of PAA solution are disturbed in the opposite way of inertia effect observed for water. The streamlines near the upstream stagnation point of cylinders are shifted upstream separating from the cylinder surface when the flow rate is higher, while streamlines in the wake appraoch closer to the downstream stagnation point. Streamlines of flow through the slit at flow rates higher than the potential flow region show that a pair of vortices is formed upstream the slit entrance, while the streamlines remain attached to the downstream wall after passing the slit.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Cu
2ZnSnS
4 (CZTS) thin films were prepared by sulfurizing precursors deposited by electroplating. The precursors (Cu/Sn/Zn stacked layers) were deposited by electroplating sequentially onto ...Mo-coated glass substrates. Aqueous solutions containing copper sulfate for Cu plating, tin sulfate for Sn plating and zinc sulfate for Zn plating were used as the electrolytes. The precursors were sulfurized by annealing with sulfur at temperatures of 300, 400, 500 and 600
°C in an N
2 gas atmosphere. The X-ray diffraction peaks attributable to CZTS were detected in thin films sulfurized at temperatures above 400
°C. A photovoltaic cell using a CZTS thin film produced by sulfurizing an electroplated Sn-rich precursor at 600
°C exhibited an open-circuit voltage of 262
mV, a short-circuit current of 9.85
mA/cm
2 and an efficiency of 0.98%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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