Transient degradation and recovery of CdS/CdTe solar cells

Changing the bias voltage, light intensity and temperature during stress can induce transient degradation or recovery in V_OC of CdTe solar cells. Simulated day/night cycles leads to daily degradation in the light and recovery in the dark. Greater recovery in the dark and less bias dependence is correlated with better overall stability. These transients complicate the correlation between cell (indoor) and module (outdoor) performance. Results are consistent with changes in electronic states and recombination. No single stress protocol is likely to identify all instability mechanisms.