CHClF2 gas mixtures to activate all-sputtered CdS/CdTe solar cells

Solar cell production process entirely based on sputtering deposition is considered the most suitable for industrial applications. Based-CdTe solar cells need activation treatment usually performed by CdCl2 saturated solution bath followed by high temperature annealing. Liquid, flammable and toxic reagents need special care in industrial processes. In this work, alternative activation treatments based on controlled gaseous atmospheres with Ar-O2-CHClF2 and Air-CHCl2 for all-sputtered CdTe solar cells were studied. Finished devices were compared to cells activated by CdCl2 saturated solution. The all-sputtered (glass/ITO/ZnO/CdS/CdTe) structures were characterized before and after the activation processes byX-ray diffraction and field emission scanning electron-microscopy. Solar cells were characterized by external quantum efficiency and current density-voltage curves. An efficiency of 11% was achieved for the solar cell activated with Ar-O2-CHClF2 gas mixture, achieving values of Voc = 0.797 V and Jsc = 25.4 mA/cm2. The quantum efficiency was around 90% in the 580-830 nm range.