A trapped charge model for the transient effect in CIGS solar cells

The authors present a model for the transient effects observed in CIGS based solar cells. By considering charge trapping and de-trapping in the CdS layer of the structure, they provide a mechanism for the observed cyclic performance changes. To complement the physical model, an AMPS computer model of a CIGS device was created and used to show that the effects of trapped charge correspond to the experimentally measured changes. The charge buildup in the CdS region is shown to reduce only the fill factor of devices, and as the computer model shows, this effect may be alleviated with higher n-type doping in the CdS layer.