Device and Physical Properties of Solar Cells with Thin CdTe Absorbers

Tellurium is considered as a rare element and there are controversial reports on its real amount available on the earth. It has been reported that with the current CdTe technology in the market it would be difficult to produce more than about 30 GW per year. On the other hand reducing dramatically CdTe thickness, the production could increase substantially up to 150/250 GW per year (depending on the thickness reduction of the absorber). In our laboratory we have prepared solar cells by depositing CdTe with different thicknesses: from 0.7 to 6 m. Ultra-thin absorber (between one and two microns) devices have demonstrated efficiencies around 10%, higher efficiencies are reported for thicker CdTe absorbers. The structural properties of the absorbers have been studied by X-ray diffraction spectroscopy and by atomic force microscopy. Finished solar cells were analyzed by electrical characterization (currentvoltage,voltage, drive level capacitance profiling, capacitancevoltage and admittance spectroscopy).