Secondary barriers in CdS- CuIn1-x Gax Se2 solar cells

Abstract

Previous work on CdS- CuInSe2 (CIS) solar cells, which reported distortions of their current-voltage (J-V) curves under red illumination, is expanded in this work to include CdS- CuIn1-x Gax Se2 cells with variable Ga and CIS cells with variable CdS thickness. Different amounts of J-V distortion were observed in these cells under red light. The details are in good agreement with predictions of a photodiode model, in which a secondary barrier caused by the positive conduction-band discontinuity (spike) at the buffer-absorber interface is responsible for the current limitation. The illumination of the cell with high-energy photons lowers the barrier due to buffer photoconductivity, and thus removes the J-V distortion. © 2005 American Institute of Physics.