Fabrication of Cu(In,Ga)Se2 solar cell with ZnS/CdS double layer as an alternative buffer

A ZnS/CdS double layer was developed to enhance the light transmittance by ZnS, while keeping the good heterojunction with CIGS by CdS layer. Through optimization of deposition process, very thin and uniform CdS layer was deposited to minimize the light blocking effect in short wavelength region. No cracks have been observed in the ZnS/CdS double layer. The optical transmittance of the ZnS/CdS double layer was as high as that of ZnS single layer. The short-circuit current of CIGS solar cell was increased with the ZnS/CdS layer. However, the fill factor was decreased compared to the CIGS solar cell with CdS single layer, suggesting a thinner ZnS is required. At present, the best cell has yielded an efficiency of 10.08%.