Effect of pinhole and its recovery in CdS/CdTe solar cell through fabrication simulation

Abstract

The performance of a solar cell is affected by pinhole formation during the deposition of the very thin cadmium sulfide (CdS) film. Insertion of a zinc oxide (ZnO) buffer layer between the top transparent conducting oxide and the window layer can help in the recovery of the performance of the pinhole-affected cadmium sulfide/cadmium telluride (CdTe) solar cell. The authors have made a deeper study about pinhole formation and its effect through modelling and simulation to investigate the influence of the pinhole on cell performance and its recovery. Both surface recombination and trap-assisted tunnelling recombination in the cadmium sulfide/cadmium telluride interface region have been considered separately to investigate thoroughly the effect of a pinhole on the space-charge region and open-circuit voltage (V OC). An efficiency η of 18·67%, an open-circuit voltage V OC of 0·656 V, a short-circuit current I SC of 0·368 A and a fill factor of 76·7% after insertion of the buffer layer have been achieved. However, a poor performance (η of 2·55%, V OC of 0·184 V, I SC of 0·302 A) has been exhibited by the pinhole-affected cell.