Multiple-interface tracking of degradation process in organic photovoltaics

The investigation of the stability in organic photovoltaics has been focused on individual components via localized and destructive analysis, which is limited to broken devices, instead of an operational OPV, and unable to obtain correlated information of degrading interfaces. DC biased AC impedance spectroscopy is employed here, to track multi-interface degradation without breaking the device. By varying DC bias, individual interface degradation is revealed via current density and capacitance versus voltage plots. While one of the impedance semicircles is linked to the interface of P3HT:PCBM, the other represented the interface between the mixture and metal electrode, involving metal oxide in an aged device. The results confirm that, more than one degradation process take place simultaneously at individual interfaces.