Bi-layered back contact structures consisting of Mo-capping and Na-doped Mo layers have been investigated for the purpose of providing extra Na for CuIn 0.7 Ga 0.3 Se 2 (CIGS) absorbers for high efficiency solar cells on a stainless steel substrate. This approach utilizing a thick back contact layer does not require a buffer layer on the substrate. The cell performance depends largely on the content of Na in the Mo:Na layer as Na easily diffuses into the absorber layer. The best cell efficiency of 15.04% is obtained for the cell incorporating the 600 nm Mo-capping and 900 nm 10% Na-incorporating Mo layers. This enhancement is attributed mainly due to the substantial increase of V oc as a result of higher carrier concentration and lower leakage current of the extra Na-involved absorber.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Surfaces, Coatings and Films