Process development of sublimated Cu-free CdTe solar cells

CdCl2 treatment by evaporation has been optimised for CdTe solar devices without a copper annealing process. In this work, we show that the performance of CdTe devices follow a curvilinear trend by increasing the amount of chlorine used for the passivation treatment. It has been observed that the maximum of the curve represented the best performing devices. However, excessive CdCl2 caused deleterious effect on electrical performances of the cells. The PL imaging analysis has been found to be a useful technique to assess the effectiveness of the activation treatment due to the presence of chlorine in CdS thin films. Electrical characterisation has been performed on each device and PL imaging analysis has been used to validate the performances of the CdTe solar cells. Results showed that the optimum performance corresponded to the highest PL image emission signal.